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An important facility for 9th class students preparing for short questions chemistry 9th class chapter 1 of BISE. Get hundreds of questions to prepare and get better marks in 9th chemistry
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Our database contains a total of 0 questions for chemistry Short Questions. You’ll prepare using this huge databank.

Question: 1
Define atomic mass unit. Why is it needed?
Answer: 1
1-861
Atomic Mass Unit: The unit for relative atomic masses is called atomic mass unit. Symbol:Its symbol is amu. One atomic mass unit is 1/12th the mass of one atom of carbon -12th the mass of one atom of carbon-12th . When this atomic mass unit is expressed in grams, it is : 1 amu=1.66 x 10-24 g
Question: 2
Name one solid, one liquid and one gaseous element present at room temperature?
Answer: 2
2-861
Solid : Sodium, Iron Liquid: Bromine and Mercury Gas: Oxygen , Nitrogen, and Chlorine
Question: 3
How can you justify that air is a homogeneous mixture. Identify substances present in it?
Answer: 3
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Air is a mixture formed by be the physical mixture of the substances like nitrogen, oxygen, carbon dioxide, noble gases and moisture and it has same composition throughout. So,it is homogenous mixture.
Question: 4
On the basis of properties, elements are divided into which groups?
Answer: 4
4-861
On the basis of properties elements are divided into metals, non-metal, and metalloids
Question: 5
Give the composition of Earth Crust with respect to three major elements.
Answer: 5
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Earth Crust is formed by three major elements having following percentages. Oxygen 47% Silicon 28% Aluminum 7.8%
Question: 6
Define Relative atomic mass?
Answer: 6
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"Relative atomic mass of an element is the average masses of atoms of that element as compound to 1/12th the mass of one atom of Carbon-12 isotope. Example: Mass of Na = 23 amu When atomic mass unit is expressed in grams, it is. 1 amu = 1.60x10-24 g
Question: 7
Define Chemistry?
Answer: 7
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The Branches of Science which deals with the composition, structure, properties and reactions of matter is called chemistry.
Question: 8
What is the significance of the symbol of an elements?
Answer: 8
8-861
Significance of the symbol of an element: Symbols are used for elements instead of writing of their complete names. So, it takes less time save time and element can be recognized by that symbol in all over the world. For example oxygen,sulphur, Nitrogen
Question: 9
What is the application of Inorganic Chemistry?
Answer: 9
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It has application in every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 10
Define Industrial Chemistry and Analytical Chemistry.
Answer: 10
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Industrial Chemistry: "This branch of chemistry is related to the the industrial processes" It is associated with studies of properties uses and application of techniques for the preparation of industrial sales on large scale.
Question: 11
What are the uses of Nuclear Chemistry?
Answer: 11
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It has vast application in medical treatment, preservation of food and generation of electrical power through nuclear reactors.
Question: 12
What is meant by variable valency?
Answer: 12
12-861
Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3
Question: 13
Define Empirical formula and give examples.
Answer: 13
13-861
"It is the simplest whole number ratio of atoms present in a compound" Example: Empirical formula of benzene(C6H6) is CH Empirical formula of Hydrogen peroxide (H2O2) is HO
Question: 14
Find out the mass of 3 moles of oxygen atoms.
Answer: 14
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3 x 16 = 48 g of oxygen are present in 3 moles.
Question: 15
What is radical
Answer: 15
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An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e.g. Hydronium H2O and carbonate CO3-2
Question: 16
What is teh relationship between mass and mole of a substance?
Answer: 16
16-861
The relationship between mass and mole of substance is given as following mass of substance = No of moles x Molar mass of substance
Question: 17
How many atoms are present in one gram atomic mass of a substance?
Answer: 17
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One gram atomic mass of a substance is equal to Avogadro's number in which 6.023 x 1023 atoms are present
Question: 18
Give electronic configuration of hydrogen ?
Answer: 18
18-861
Electronic configuration of 11H is 1s1
Question: 19
Differentiate between empirical and molecular formula.
Answer: 19
19-861
Empirical formula: it is the simplest whole number ratio of atoms present in a compound
e.g. Empirical formula of benzene is CH.
Question: 20
Which term is used to represent the mass of 1 mole of molecules of a substance?
Answer: 20
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Gram molecular mass
Question: 21
Give one example each of the use of radioactive isotope in medicine and radiotherapy ?
Answer: 21
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Radioactive isotopes is used in medicine
Iodine 131
Radioactive isotopes used in radiotherapy
P-32
Sr-90
Co-60
Question: 22
Difference between homogeneous and heterogeneous mixture.
Answer: 22
22-861
Homogeneous mixture: Mixtures that have uniform composition throughout are called homogeneous mixtures.
example: Milm, Brass, Ice-cream.
Question: 23
Is atomic mass unit a SI unit of an atomic mass?
Answer: 23
23-861
Yes , Atomic mass unit is SI unit of atomic mass.
Question: 24
What is Radical?
Answer: 24
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An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e.g. Hydronium and carbonate.
Question: 25
What is valency?
Answer: 25
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The combining capacity of an element with other elements is called valency For example. Valency of carbon is 4
Question: 26
Give the composition of milk.
Answer: 26
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Milk is a mixture of calcium , water, sugar, fat, proteins, minerals, salts and vitamins.
Question: 27
What is the relationship between atomic number and atomic mass?
Answer: 27
27-861
The relationship between atomic number and atomic mass is as following. A = Z = n Where A = mass number Z = Atomic number n= no of neutrons
Question: 28
What is atomic number, how it is represented?
Answer: 28
28-861
"The atomic number of an element is equal to the number of protons present in the nucleus of its atoms." Representation:It is represented by "Z"
Question: 29
Why atomic mass of an atom is defined as relative atomic mass?
Answer: 29
29-861
ATomic mass of an atom is defined as relative atomic mass, because atomic mass of an atom is the mass which compares or relates with 1/12th mass of carbon 12 isotope.
Question: 30
Which branch of chemistry deals with the structure and properties of naturally occurring molecules.
Answer: 30
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"Organic chemistry deals with the structure and properties of naturally occuriring molecules."
Question: 31
What is the difference between Mendeleev's and modern periodic law ?
Answer: 31
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Mendeleev's periodic law :
Properties of the element are periodic function of their atomic masses is called Mendeleev's periodic law

Question: 32
What is atomic number of phosphorous ? Write down its electronic configuration .
Answer: 32
32-861
Atomic number of phosphorous (P) is 15
Electronic configuration
1s2 , 2s2 ,2p6 ,3s2 ,3p3
Question: 33
What is the relationshp between atomic number and atomic mass?
Answer: 33
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The relation between atomic number and atomic mass is as following A = Z + n
Question: 34
Define empirical formula and give examples.
Answer: 34
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It is the simplest whole number , ratio of atoms present in a compound." Empirical formula of benzene Empirical formula of Hydrogen peroxide
Question: 35
Define Biochemistry.
Answer: 35
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"It is branch of chemistry in which we study the structure, composition and chemical reactions of substances found in living organisms .
Question: 36
What is the relationship between empirical formula and formula unit.
Answer: 36
36-861
All the organic compounds are represented by formula unit. Formula unit is also and empirical formula of Ionic compounds.
Question: 37
Which branch of chemistry deals with energy of atoms and its uses in daily life.
Answer: 37
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Nuclear chemistry deals with energy of atoms and its uses in daily life.
Question: 38
How many electrons will be in M-shell of an atom having atomic number 15 ?
Answer: 38
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K L M
2 8 5
5 electrons are present in M shell of an atom having atomic number 15
Question: 39
What is free radical? Give example.
Answer: 39
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"Free radicals are atoms or group of atoms possessing odd number of electrons". Example: It is represented by putting a dot over teh symbol of an element e.g. H+,Cl-,H3C, Free radical are generated by teh homolytic breakage of the bond between 3 two atoms when the absorb heat or light energy A free radical is extremely reactive species as it has the tendencyto complete its octel.
Question: 40
Why do the isotopes of an element have different atomic number masses?
Answer: 40
40-861
As isotopes of an element have same atomic mass . Mass number depends upon number of protons and neutrons . Isotopes of an element have the same number of proton but only differ in their neutrons number
Question: 41
Explain difference between physical chemistry and biochemistry .
Answer: 41
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Physical chemistry: physical chemistry IS defined as the branch of chemistry that deals with the relationship between the composition and physical properties of matter , along with changes in them
Question: 42
In which branch of chemistry behaviour of gases and liquid is studied?
Answer: 42
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The behaviour of gases and liquids is studied in the branch of chemistry called physical chemistry.
Question: 43
Which branch of chemistry deals with preparation of paints and papers?
Answer: 43
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"Industrial chemistry deals with preparation of paints and papers."
Question: 44
In which branch of chemistry deals with preparation of paints and papers?
Answer: 44
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"Industrial chemistry deals with preparation of paints and papers".
Question: 45
How is periodicity of properties dependent upon the numbers of protons in an atom ?
Answer: 45
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In periodic table from left to right number of protons increase regularly by 1 from atom to atom . Therefore nuclear charge will increase . Due to change in nuclear charge the properties of an atom were found repeating after regular intervals . Hence periodicity of properties dependent upin the number of protons in an atom
Question: 46
How many sub-shells are there in second shells ?
Answer: 46
46-861
Two sub-shells s and p are present in second shell L
Question: 47
What are Lanthanide and actinide series ?
Answer: 47
47-861
Due to space problem two series of elements are placed below periodic table
Question: 48
What do you mean by 1 atom carbon and 1 gram atom of Carbon.
Answer: 48
48-861
One atom of carbon has its atomic mass which is 12 amu . But when this mass of carbon atom is expressed in gram then it is known as gram atomic mass. As 1 gram of carbon =12.0 g.
Question: 49
Differntiate between biochemistry and industrial chemistry .
Answer: 49
49-861
Biochemistry : Biochemistry is the branch of chemistry in which w study the structure , composition , and chemical reaction of substances found in living organisms
Question: 50
If an element has atomic number 13 and atomic mass 27 , how many electrons are there in each atom of the element?
Answer: 50
50-861
Atomic number of an element (Z) =13
Mass no.of an atom (A) =27
A the total number of electrons in an atom is equal to its atomic number (Z) ,so it will have 3s electrons
Question: 51
What is the reason of arranging elements in a group?
Answer: 51
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The reason of arranging of elements in a groups, is that they have same electronic configuration and same properties so they form a family.
Question: 52
How many atoms are in I amu and I g of hydrogen .
Answer: 52
52-861
1 amu and 1 gram of hydrogen has 6.022x1023 atoms.
Question: 53
What are blocks ? How many blocks are present in periodic table ?
Answer: 53
53-861
On the basis of completion of a particular sub shell , element with similar sub-shell electronic configuration are referred as a block of elements . Four blocks are present in periodic table . s,p,d,f
Question: 54
Why shielding effect of electron makes action formation easy ?
Answer: 54
54-861
As we move down in a group more and more shells come come between valence shell and the nucleus of atom , additional shell reduce the electrostatic force of attraction felt by the electron present in the outermost shell , and the shielding effect increases resultantly , and the electrons can be taken away , easily and cations form
Question: 55
How many electrons are present in sub-shell ?
Answer: 55
55-861
s can have 2 electrons
p can have 6 electrons
d can have 10 electrons
f can have 14 electrons
Question: 56
If 16 gram of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams.
Answer: 56
56-861
16 g of oxygen = 1 mole of oxygen
Mass of one atom of oxygen = 16 grams.
Question: 57
Why does an electron fill 2p orbital and then 3s and then 3s orbital ?
Answer: 57
57-861
As we know that electrons that electrons fill the shells as order of their increasing energy , i-e lower energy level is occupied first then the high energy level and so on . 2p orbital has lower energy than 3s orbital that is why 2p orbital is first filled and then 3s orbital
Question: 58
What is the significance of the symbol of an element ?
Answer: 58
58-861
Symbol means identification , in chemistry it is used for the representation of chemical name of an element . In chemical equation whole name of an element is difficult to write , because the formula or chemical equation becomes too lengthy . Thus symbol makes an easy representation and understanding in this case
Question: 59
Why HCl has dipole-dipole forces of attraction?
Answer: 59
59-861
HCl has dipole-dipole forces of attraction. The unequal sharing of electrons between two different types of atoms make one end of molecule slightly positive and other end slightly negatively charged. As shared pair of electron is drawn towards more electronegative atom, it is partially negatively charged. as chlorine in hydrogen chloride. 'The other end automatically becomes partially positively charged.
Question: 60
Define Biochemistry ? Describe scope of biochemistry and give two examples of biochemistry.
Answer: 60
60-861
The branch of science concerned with the chemical and physico-chemical processes and substances that occur within living organisms.
Question: 61
is the mass of 1 mole of Oxygen and 1 mole of Sulphur same.
Answer: 61
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No, the mass of 1 mole of oxygen and 1 mole of sulphur atom is not same.
Question: 62
What type of elements have tendency of sharing of electrons?
Answer: 62
62-861
If bond formation is between similar atoms or between the atoms that have comparable electronegativities. then the chemical bond formation is by sharing of electrons
Question: 63
Why cesium requires little energy to release its one electron present in the their outermost shell ?
Answer: 63
63-861
Cesium is the 2nd last element of 1st group . It has large size and less force and less force of attraction between the nucleus and valence electron , as a result small amount of energy is required to remove electron from the valence shell
Question: 64
Who discovered proton , electron , neutron ?
Answer: 64
64-861
In 1886, Goldstein discovered positively charged particles called protons . In 1897 , J.J Thomson found in an atom , the negatively charged particles known as electron . In 1932 James Chadwick discovered neutron
Question: 65
How many elements are in 3rd period, write their names and symbols?
Answer: 65
65-861
There are eight elements in 3' period, sodium(Na), magnesium(Mg) .aluminium (AI).silicon(Si),phosphorus(P),sulphur(S),chlorine(Cl),argon(Ar)
Question: 66
Which electrons are involved in chemical bonding?
Answer: 66
66-861
Only valence shell electrons are involved in chemical bonding
Question: 67
How many times is 1 mole of oxygen atom heavier than 1 mole of hydrogen atom?
Answer: 67
67-861
One mole of oxygen atom is 16 times heavier than the one mole of hydrogen.
Question: 68
Why atomic number is more fundamental property to arrange elements than atomic mass?
Answer: 68
68-861
Due to two reasons :
1: It increase regularly from element to element
Question: 69
Define industrial chemistry and analytical chemistry ?
Answer: 69
69-861
Industrial chemistry : It is the branch of chemistry that deals with the manufacturing of chemical compounds on commercial scale
Question: 70
How many neutrons are present in C-12 and C-13 ?
Answer: 70
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C-12 C-13
P=6 P=6
N=12-6=6 N=13-6=7
Question: 71
What are application of inorganic chemistry.
Answer: 71
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It has application is every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 72
Describe atIeast two necessary conditions for the formation of a covalent bond.
Answer: 72
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Iwo necessary conditions for the formation of covalent bond are: (.) The electronegativity difference between atoms must be less. So. that the shared pair of electrons is attracted by both the atoms equally. (i1) Maximum 3 to 6 electrons are present in their valence shells
Question: 73
Calculate no of carbon atoms in one mole C6 H12 O6
Answer: 73
73-861
6 atoms of carbon are present in one mole of glucose
Question: 74
Define symbol and valency with example .
Answer: 74
74-861
Symbol : The representation of any element with one or two english letters is called symbol.
Question: 75
How can you prove that angular momentum is quantized ?
Answer: 75
75-861
mvr =nh/2π
The angular momentum of first orbit is (n=1)
mvr = 6.63x10-34/2x 3.14

Question: 76
How many atoms are present in 16 g of O and 8g of S?
Answer: 76
76-861
16 grams of oxygen has 6.022 x 1023atoms and 8 grams of sulphur has 1.055x1023atoms.
Question: 77
What is the capacity of the K,L,M,N shells ?
Answer: 77
77-861
K shell can accommodate 2 electron
L shell can accommodate 8 electrons
M shell can accommodate 18 electrons
N shell accommodate 32 electrons
Question: 78
Why does sodium lose one electron and attain +1 charge?
Answer: 78
78-861
Sodium has one electron in its valence shell. So. it loses its outer most electrons to complete its octet and become positive ion .i.e. Na+
Question: 79
Define modern periodic law ?
Answer: 79
79-861
In 1913 H.Moseley given Modern law
Properties of elements are periodic function of their atomic masses
Question: 80
Why the bond between an electropositive and electronegative atom is ionic in nature ?
Answer: 80
80-861
Electropositive elements lose electrons while electronegative elements gain electrons . That's why both combine and forms ionic bond
Question: 81
Name the elements represented by the following symbols W, Ba , Hg and Na
Answer: 81
81-861
Tungsten W , Barium B , Mercury Hg , Sodium Na
Question: 82
Which carbon isotope use in carbon dating ?
Answer: 82
82-861
C-14 used in carbon dating
Question: 83
What do you mean by group or median in periodic table ?
Answer: 83
83-861
The horizontal rows in periodic table called periods and vertical columns in the periodic table are called groups
Question: 84
How do atoms follow octet rule?
Answer: 84
84-861
Atoms follow octet rule to have the noble gas electronic configuration. For this purpose atoms attain 8 electrons in the outermost shell either by sharing. by losing or by gaining electrons
Question: 85
How many elements are in first period and what are their names and symbols?
Answer: 85
85-861
There are two elements in first period, hydrogen (H), helium(He)
Question: 86
Write any two elements found in the liquid state at room temperature .
Answer: 86
86-861
Mercury and bromine are two elements found in the liquid state at room temperature
Question: 87
Why cesium (At.No.55 ) requires little energy to release its one electron present in their outermost shell ?
Answer: 87
87-861
Cesium is the 2nd last element of 1st group . It has large size and less force of attraction between the nucleus and valence electron , as a result small amount of energy is required to remove electron from the valence shell
Question: 88
How does homogeneousmixture differ from heterogeneous mixture?
Answer: 88
88-861
The mixture that has uniform composition throughout is called homogeneous mixture which composition is not uniform throughout e.g. soil, rock and wood etc.
Question: 89
Why the electrons move freely in metals ?
Answer: 89
89-861
This is because the valence shell electrons loosely held by nucleus of an atom . There is the weak force of attraction present between nucleus and the mobile valence electrons . Therefore valence electrons move freely in metals
Question: 90
Differentiate between lone pair and bond pair of electron.
Answer: 90
90-861
Lone Pair
The non-bonded electron pair available on an atom. like the one lone pair is available on nitrogen in ammonia is called a lone pair
Question: 91
Define electronic configuration ?
Answer: 91
91-861
Electronic configuration : The distribution of electrons around the nucleus in various shells and sub-shells according to increasing energy , is called electronic configuration
Question: 92
Define nuclear fission reaction .
Answer: 92
92-861
A reaction in which heavy nuclear splits up into two nuclei by absorbing show moving next ions
Question: 93
Define chemistry ? Explain two branches of chemistry .
Answer: 93
93-861
Chemistry : The Branch of science which deals with the composition , structure, properties and reaction of matter is called chemistry
Question: 94
Define groups ?
Answer: 94
94-861
The vertical columns in periodic table are called groups . Numbered from 1 to 18
Question: 95
In which pattern modern periodic table was arranged?
Answer: 95
95-861
According to increasing atomic number.
Question: 96
Write difference between physical and chemical properties .
Answer: 96
96-861
Chemical properties :
1: It depends upon the composition of the substance
2: When a substance undergoes a chemical change , its composition change and a new substance is formed .
Example : When hydrogen react with oxygen , it form water , chemical change
Question: 97
Ionic compounds are solids. Explain
Answer: 97
97-861
Ionic compounds are made up of positively and negatively charged ions . Thus they consists of ions and not molecules . These positively charges ions are held together in a solid or crystal form
Question: 98
Why the rate of diffusion gases is rapid than that of liquids ?
Answer: 98
98-861
The rate of diffusion of gases is rapid than that of liquid due to the less attractive forces among the gas molecules than liquids . Gas molecule moves randomly and spread around
Question: 99
What is ionic bond? Give an example.
Answer: 99
99-861
Definition: A chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond.
Question: 100
Why the size of atom does not decrease regularly in periods ?
Answer: 100
100-861
The atomic size does not decrease regularly in periods due to presence of transition elements . The size of atom first decreases then increases
Question: 101
Define isotope ?
Answer: 101
101-861
Isotopes are defined as the atoms of elements that have same atomic number but different mass number
Question: 102
What type of covalent bond is formed in nitrogen molecule?
Answer: 102
102-861
In nitrogen molecule. three bond pairs are involved in bond formation. This type is called triple covalent bond. Three small lines are used to indicate these three pairs of electrons between those atoms in the molecules of such compounds.
Question: 103
Define atomic number and atomic mass .
Answer: 103
103-861
Atomic mass :
1: The sum of number of protons and neutrons present in the nucleus of an atom is called atomic mass
2: It is represented by A
Example : Atomic mass of carbon is 12
Question: 104
Why is the hold of nucleus over the outermost electrons in metal weak ?
Answer: 104
104-861
The hold of nucleus over the outermost electrons is weak because of large size atoms and greater number of shells in between nucleus and valence electrons . Furthermore ,because of low ionization potentials , metals have the tendency to to loose their outermost electrons easily
Question: 105
What are SI units of atomic radius ?
Answer: 105
105-861
Pico meter (pm) =10-12m
Question: 106
Define organic chemistry and which industries covered by it
Answer: 106
106-861
Organic chemistry : it is the study of covalent compounds of carbon and hydrogen and its derivatives
Question: 107
What are the defects of Mendeleev's periodic table or why improvement was make in Mendeleev's periodic table?
Answer: 107
107-861
There are two defects in Mendeleev's periodic table:

Question: 108
How is the goiter in thyroid gland detected ?
Answer: 108
108-861
Iodine -131 is used fir the diagnosis of goiter in thyroid gland
Question: 109
Explain how anode rays are formed from the gas taken in the discharge tube .
Answer: 109
109-861
Anode rays are produced when the cathode rays collide with residual gas molecules present in the discharge tube and ionize them as follows
M+ le-➜ M+ +2e-
Question: 110
What is diffusion ? Explain with example .
Answer: 110
110-861
Diffusion : The process in which molecules more from the area of higher concentration move to the area of lower concentration until the state of equilibrium is achieved is called diffusion
Question: 111
How a covalent bond becomes polar?
Answer: 111
111-861
When a covalent bond is formed between two different atoms having different electronagetivity then the bond pair of electron will not be attracted equally by the bonded atoms as a result partial positive and negative charges appear on atoms and covalent bond becomes polar.

Question: 112
Write name of any two elements found in gaseous state
Answer: 112
112-861
Nitrogen and oxygen both found in gaseous state
Question: 113
Why do atoms react ?
Answer: 113
113-861
It is an universal rule that everything in this world tends to become more stable . Atoms achieve stability by attaining electronic configuration of inert gases (He ,Ne ,or Ar ) . Having 2 or 8 electrons in the valence shell is sign of stability . Attaining two electrons in the valence shell is called duplet rule while attaining 8 electrons in the valence shell is called octet rule
Question: 114
An element has 5 electron in M shell . Find out its atomic number ?
Answer: 114
114-861
The number of this element will be 15
Question: 115
What is classical theory of radiation . How it is differ from quantum theory ?
Answer: 115
115-861
According to classical theory of radiation electrons being the charge particle should release energy continuously and they should ultimately fall into a nucleus . It differ from quantum theory because quantum means fixed energy it is the smallest amount of energy that can be emitted or absorb as electromagnetic radiation
Question: 116
Explain plum pudding theory .
Answer: 116
116-861
Thomson put forth his plum pudding theory . He postulated that atoms were solid structures of positively charge with tiny negative particles stuck inside . It is like plum in the pudding
Question: 117
Differentiate bonding electrons and non-bonding electrons•
Answer: 117
117-861
The valence electrons which are involved in chemical boding, are termed as bonding electrons. e.g.
The valence electron of sodium is bonding electrons
11Na K L M
2 8 1
Question: 118
Define periodicity ?
Answer: 118
118-861
Properties of elements were found repeating after regular intervals in periodic table it is the periodicity
Question: 119
What is mean by cation and anion? Explain with example.
Answer: 119
119-861
Cation:
The cations are formed when an atom loses electrons from its outmost shells. For example cations are Na+ , K+, Ca+2
Na ______> Na+ + 1e-
Question: 120
Which gasses are present in air ? Write their names .
Answer: 120
120-861
Oxygen , nitrogen , carbon dioxide , argon are major gasses present in air
Question: 121
Why and how are element arranged in 4th period ?
Answer: 121
121-861
Elements are arranged in 4th period according to increasing atomic number . The 4th period contains 18 elements beginning with potassium and ending with krypton . As a rule . 4th period elements fill their 4th subshells in that order however there are exception such as chromium
Question: 122
How is periodicity of properties dependent upon the number of protons in an atom ?
Answer: 122
122-861
In periodic table from left to right number of protons increases . Due to change in nuclear charge the properties of an atom were found repeating after regular intervals . Hence periodicity of properties dependent upon the number of proton in an atom
Question: 123
Why the rate of diffusion of gases is rapid than that of liquid ?
Answer: 123
123-861
The rate of diffusion of gases is rapid than that of liquid because the movement of gas molecule is rapid as compared to liquid , So due to random motion and collision gases diffuses rapidly
Question: 124
Electronic configuration of Cl- ion
Answer: 124
124-861
Cl-1s2 ,2s2,2p6 ,3s2 ,3p6
Question: 125
How the properties of elements repeat after regular intervals?
Answer: 125
125-861
The modern periodic table is based upon the arrangement of elements according to increasing atomic number. When the elements are arranged according to increasing atomic number from left to right in a horizontal row. properties of elements were found repeating after regular intervals
Question: 126
Why shielding effect of electrons makes action formation easy ?
Answer: 126
126-861
As we move down in a group more and more shells come between valence shell and the nucleus of an atom , additional shell reduce the electrostatic force of attraction felt by the electron present in the outermost shell and the shielding effect increases resultantly , and electrons can be taken away , easily and cations form
Question: 127
How many members are in group 17, is there any liquid, what is its name?
Answer: 127
127-861
There arc five members in group 17 which are F,C1 .Br , I and At. Only one liquid element is present named as bromine Br).
Question: 128
Why melting point and boiling points of ionic compounds are high?
Answer: 128
128-861
Melting and boiling of ionic compounds are high because thy consists of positive and negative ions . There exists very strong electrostatic interaction between these charged ions . That is why a lot of force is required to break these forces
Question: 129
Differentiate between nuclear chemistry and environmental chemistry .
Answer: 129
129-861
Environmental chemistry:
1 :The branch of chemistry in which we study about components of the environment and effect of human activity on the environment
2 :it is also concerned with other sciences like biology, geology
3: Save environment from pollution

Question: 130
Define periods ?
Answer: 130
130-861
Seven horizontal rows present in periodic table are called periods . Numbered from 1 to 7
Question: 131
Define molecular mass and give example .
Answer: 131
131-861
Molecular formula that shows actual number of atoms of each element present in molecules of that compound
Question: 132
Why do atoms form chemical bonds?
Answer: 132
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Atoms achieve stability by attaining electronic configuration of inert gases ns2 or ns2,np6 Atoms combine with one another. which is called chemical bond.
Question: 133
What are Dobereiner's triads ?
Answer: 133
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A German chemist Dobereiner's observed relationship between atomic masses of several groups of three elements called triads . In triads the central and middle element had atomic mass average of the other two elements
Question: 134
Ionic compounds conduct electricity in solution or molten form. Why?
Answer: 134
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Ionic compounds conduct electricity in solution or molten form because in these two states ionic compounds have free ions in them. When these free ion move in solution or molten gate they become conductor of electricity
Question: 135
Why big size covalent molecules have high melting and boiling points?
Answer: 135
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Bigger molecules with three dimensional bonding form covalent crystals which are very stable and have high melting and boiling points.
Question: 136
Write down the name of any two elements which were discovered in early ages .
Answer: 136
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Following elements were discovered in early ages
Question: 137
Give the trend of ionization energy in a period ?
Answer: 137
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If we move from left to right in a period the value of ionization energy increases . Because the size of atom reduce and valence electrons are held strongly by the electrostatic force of nucleus . Therefore elements on left side of the periodic table have low ionization energies as compared to those on right side of the periodic table
Question: 138
Define Mendeleev's periodic table ?
Answer: 138
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A Russian chemist arranged elements (63) discovered at that time according to increasing atomic mass . ' Properties of elements are periodic function of their atomic masses '
Question: 139
Ionic bond is stronger than covalent bond . Explain .
Answer: 139
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Ionic bond formed between two opposite charges and electrostatic forces . That's why ionic compound is stronger than covalent bond
Question: 140
Which is the simplest form of matter?
Answer: 140
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Gas is the simplest form of matter.
Question: 141
What is meant by element ? Explain with example .
Answer: 141
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Element is a substance which is made up of some types of atom , having same atomic number and it cannot be dissolved into simple substances by ordinary chemical means
Question: 142
Write any two applications of inorganic chemistry.
Answer: 142
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Inorganic chemistry has applications in following aspects of the chemistry industry
Question: 143
Define matter and mixture .
Answer: 143
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Matter : anything that has mass and occupies space is called matter . Matter exists in three physical states , solid , liquid , gas
Question: 144
What is the empirical formula of acetic acid ? Calculate its molecular mass.
Answer: 144
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Empirical formula of acetic acid CH2O
Question: 145
Which is lighter one aluminium or gold?
Answer: 145
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Aluminum is lighter than gold because density or aluminium is 2.70 gcm'-3 While of gold is 9.3 gcm-3
Question: 146
What do you mean by induced dipole?
Answer: 146
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The charges in one molecule creates charges in other molecules these charges are called induced dipole.
Question: 147
Why has water polar covalent bond ?
Answer: 147
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Water has polar covalent bonds because there is a difference of electronegativity (1.3) between H and O atoms . There will be an unequal attraction for the bond pair of electron between H and O atoms . It will results in the preparation of polar covalent bond
Question: 148
Write two properties of gases
Answer: 148
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1: Molecules of gases are always in state of continuous motion . They have very high K.E .
Question: 149
What is difference between polar and non-polar covalent bonds, explain with one example of each?
Answer: 149
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Polar Covalent Bonds Non-Polar Covalent Bonds
If the covalent bond is formed between two different types of atoms then bond pair of electrons will not be attracted equally by the bonded atoms. One of the atoms will attract the bond pair of electrons more strongly than the other one. They form polar covalent bond. For example: H+—F', H+—CI-
Question: 150
Write down the names of elements of groups 1 with their symbols .
Answer: 150
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1st group elements are called alkali metals . It consists of hydrogen (H) , lithium (Li) , sodium (Na) , potassium (K) , rubidium (Rb) and cesium (Cs) , and francium (Fr)
Question: 151
Define homogenous mixture and give example .
Answer: 151
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Homogenous mixture: The mixture having uniform composition is calledhomogenous mixture
Question: 152
Differentiate duplet and octet rule.
Answer: 152
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Duplet Rule:
Attaining two electrons in valence called duplet rule.
Example. , Li+Hefollow duplet rule.
Question: 153
What do you mean by delta sign and why it develop ?
Answer: 153
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The delta sign indicates partial positive or partial negative charge that is developed due to unequal sharing of shared pair or bonded pair of electrons
Question: 154
What is effective nuclear charge ?
Answer: 154
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The valence electron of an atom experiences less nuclear change than that of actual charge , it is called effective nuclear charge or Zeff
Question: 155
What is matter ? How many states it has ?
Answer: 155
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Matter is any thing that has mass and occupies space .
Question: 156
Why is white tin available at room temperature?
Answer: 156
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White tin available at room temperature because it is stable at room temperature above 13.2°C
Question: 157
Why 2nd ionization energy of an elements is higher than first one?
Answer: 157
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fins: energy required to remove an electron from isolated mono positive gaseous ion (M') is called second ionization energy. So more energy is required to remove second electron from a mono positive gaseous ion because there is more electrostatic force present between the nuclei and electron. M+➜M+21e-
Question: 158
Calculate the molecular mass of the carbon dioxide .
Answer: 158
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Molecular mass of the carbon dioxide
CO2 = 12+2 (16)
= 44amu
Question: 159
Which form of Sulphur exists at room temperature?
Answer: 159
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Rhombic (S8) Sulphur exists at room temperature
Question: 160
Soft drink is a mixture while water is compound . Give the reason .
Answer: 160
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Water : Water forms by the chemical reaction of hydrogen and oxygen . that's why it is called compound
Question: 161
Define atomic radius ?
Answer: 161
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The half of the distance between the nuclei of the two bonded atoms referred as atomic radius
Question: 162
Why do the bigger size atoms have more shielding effect?
Answer: 162
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In bigger size atoms the number of inner shells and inner shell electrons increases hence the shielding effect in bigger size molecules also increases.
Question: 163
Why are dipole forces of attraction not found in halogen molecules?
Answer: 163
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Dipole forces of attraction do not found in halogen molecules because they have same electronegativity and there is equal sharing of electrons.
Question: 164
What isAvogadro's number?

Answer: 164
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Avogadro,s Number:
The number of particles present in one mole of a substance is called Avogadro's number. Its value is 6.02 x 10²³. it is represented by Na
Question: 165
Why is BF3, electron deficient?
Answer: 165
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In BF3 molecule, three valence electrons of boron atom pair up with three electrons, one from each of three fluorine atoms. the boron atom even after the sharing of electron, remain shortage of 2 electrons in its outer most shell
Question: 166
Why the elements are called s and p block elements?
Answer: 166
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The elements having their valence electrons in s and p sub shell called s and p blocks elements.
Question: 167
What is the relationship between evaporation and boiling point of a liquid?
Answer: 167
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Boiling Point: .lioiling point is defined as the temperature at which the vapour pressure of a liquid becomes equal to the atmospheric pressure or any external pressure". When a liquid is heated. its molecules gain energy. The number of molecules which have moo than average kinetic energy increases. More and more molecules becomes energetic enough u overcome the intermolecular forces. Due to this, rate of evaporation increases that results increase of vapour pressure until a stage reaches where the vapour pressure of a liquid become equal to atmospheric pressure. At this stage the liquid starts boiling
Question: 168
What is difference between elements and compound ?
Answer: 168
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Compound : Compound is a substance made up of two or more elements chemically combined together in a fixed ratio by mass
Example : Water (H2O)
Question: 169
Why is the bond between an electropositive and an electronegative atom ionic in nature ?
Answer: 169
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Because ionic bond is formed due to transfer of electron from one atom to another atom is called ionic bond. The elements of Group 1 and Group 2 being metals have the tendency to lose their electrons forming positively charged ions. Whereas non-metals of Group 15 to Group 17 have the tendency to pin or accept electrons. They are electronegative elements with high electron affinities.
Question: 170
What is relationship between Empirical formula and Molecular formula ?
Answer: 170
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The relationship between Empirical formula and Molecular formulais given as
Molecular formula = (Empirical formula)*n
When n = 1,2 ,3 and so on

Question: 171
Write down any two properties of metals .
Answer: 171
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1: They show metallic luster
Question: 172
Why ionic compounds easily dissolve in water?
Answer: 172
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They dissolve easily in water because water is a polar solvent and has high dielectric constant that weakens the attraction between ions.
Question: 173
Metals arc good conductor of electricity. Why?
Answer: 173
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Metals are good conductors of electricity because metals have free electrons which are mobile in nature. Spaces are present among the atoms. Mobile electrons can move freely in these spaces. (Fence, movement/flow of electrons is known as electricity that's why metals are good conductor of electricity.
Question: 174
Why are the liquids mobile.
Answer: 174
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Liquid molecules are in continuous state of motion. They possess high kinetic energy and have weak intermolecular forces than solids That's why liquids are mobile
Question: 175
Define transition element ?
Answer: 175
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d block elements called transition element
Question: 176
What are elements in group 3 to 12 called ?elements are normal elements because their valence electrons lie in s and p sub shell
Answer: 176
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Elements in group 3 to 12 elements are normal elements because their valence electrons lie in s and p sub shell
Question: 177
Calculate the formula mass of the nitric acid .
Answer: 177
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HNO3 = 1+14+48
= 63amu
Question: 178
In which form sulphur exists at I00°C?
Answer: 178
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Sulphur exists in monoclinic form at 100"C because at room temperature sulphur exists in rhombic form. The transition temperature of sulphur is 96"C at which rhombic sulphur convened into monoclinic form.
Question: 179
What is a triple covalent bond, explain with an example?
Answer: 179
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Ans: When each bonded atom contributes three electrons, three bond pairs are involved in bond formation. This type is called triple covalent bond. Three small lines are used to indicate these three pairs of electrons between those atoms in the molecules of such compounds. For example: Nt & C2H2 Formulas: N.N.H-C==C-H
Question: 180
Classify the following into true solution and colloidal solution?
Answer: 180
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Blood, Starch solution, glucose, tooth paste, copper sulphate, silver nitrate solution. Blood. Starch solution. tooth paste are the colloidal solution. Glucose solution. copper sulphate solution and silver nitrate solution are true solution.
Question: 181
Define empirical formula and give an examples .
Answer: 181
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Empirical formula: empirical formula is a formula which represents the simplest whole number ratio of atoms present in a compound

Question: 182
Why chlorine can accept only 1 electron?
Answer: 182
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Chlorine has seven electrons in its valence shell. Chlorine being an electronegative element has the tendency to gain only one electron. They attain electronic configuration to the nearest noble gas "Ar"
Question: 183
Define Triatomic molecule and polyatomic molecule
Answer: 183
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Polyatomic molecule : The molecules which consists of many atoms calledpolyatomic molecule
Question: 184
Difference between molecular mass and formula mass.

Answer: 184
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Molecular Mass:
The sum of the atomic mass of all the elements present in a molecule is called as Molecular Mass.

Question: 185
Why noble gases are non-reactive?
Answer: 185
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The noble gases do have 2 or 8 electrons in their valence shells. It means all the noble gases have their valence shells completely filled. Their atoms do not have vacant space in their valence, shell to accommodate extra electrons. Therefore noble gases do not gain. lose or share electrons. that's why they are non - reactive
Question: 186
Define standard atmospheric pressure . What are its units ? How it is relate to the pascal ?
Answer: 186
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It is defined as the pressure exerted by a mercury column of 760 mm height at sea level
Question: 187
What is the valency id following ?
(A) Barium (B) Nitrogen (C) Sodium (D) Sulphur
Answer: 187
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Elements valency
1: Barium 2
2: Nitrogen 3
3: Sodium 1
4: Sulphur 2
Question: 188
Write two properties of covalent compounds
Answer: 188
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1: They have usually low melting and boiling points
Question: 189
Why the density of a gas is measured in gdm-3while that of a liquid is expressed in gcm-3?
Answer: 189
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The density of a gas is measured in gdm-3while that of a liquid is expressed in gcm-3because gases have large volume which is measured by large unit dm3while liquid has less volume so it is measured by small unit cm3
Question: 190
Define pressure and write its unit .
Answer: 190
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Pressure : It is defined as the force exerted by per unit surface area
Question: 191
What types of electron pairs make a molecule good donor ?
Answer: 191
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The lone pair of electron make a molecule a good donor
Question: 192
Give the characteristics properties of ionic compounds
Answer: 192
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the characteristic properties of ionic compounds. %Its: Characteristic Properties of Ionic Compounds: (I) lanai compounds are mostly crystalline solids. In I Ionic compounds in solid state have negligible electrical conductance but they are good conductors in solution and in the molten form. It is due to presence of free inns in them. lilt) Ionic compounds have high melting and boiling point example. NaCI has M.P. 800°C and B.P. 1413°C. (iv) Ionic compounds dissolves in polar solvents. Like NaCI dissolves in water.
Question: 193
What characteristics properties do the covalent compound have ?
Answer: 193
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They have usually low melting and boiling points. (ii I Flicy are usually bad conductors of electricity. lit: I hey are usually insoluble in water. IR I Bigger molecules with three dimensional bonding form covalent crystals which are very stable and hard. They have high melting and boiling points.
Question: 194
What is relative atomic mass ? How is it related to gram ?
Answer: 194
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The relative atomic mass of an element is the average mass of an atoms of that element as compared to 1/ 12th the mass of an atom of carbon -12 isotope . Atomic mass unit is represent by amu and in grams 1amu =1.66*10-24g
Question: 195
Difference between true solution and colloid solution?
Answer: 195
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True solution:Solutions are the homogeneous mixture of two or more than two components.
Question: 196
How atoms accommodate 8 electrons in their valence shells?
Answer: 196
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toms can accommodate 8 electrons in their valence shell in three.
1: By giving valence shell electrons
2:By gaining valence shell electrons
3:By sharing valence shell electrons with other atoms
Question: 197
How will you test whenever given solution is colloidal solution or not?
Answer: 197
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If the panicles scatter the path of light rays thus emitting the beam of light i.e exhibit the Tyndall effect than the given solution is colloid.
Question: 198
Define ionic bond and ionic compounds .
Answer: 198
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Ionic bond : The type of chemical bond which is formed due to complete transfer of electron from one another is called ionic bond
Question: 199
Define diatomic molecule and give example .
Answer: 199
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If a molecule consists of two atoms called diatomic molecule
Question: 200
Considering the electronic configuration of nitrogen atom, how many electrons are involved in bond formation and w hat type of covalent bond is formed?
Answer: 200
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Electronic configuration of N is 1s2.2s2.2p3 Nitrogen has 5 electrons in its valence shell. Three electrons are involved in bond formation and triple covalent bond is formed.: N = N :
Question: 201
Whether the density of a gas decreases on cooling ?
Answer: 201
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The density of gas increase by cooling because their volume decreases
Question: 202
Which are physical properties of matter ?
Answer: 202
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1: Matter exists in three physical state i-e gas, liquid , and solid
Question: 203
What is percentage-mass/mass(%m/m)?
Answer: 203
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It is the number of grams of solute in 100 grams of solution
Question: 204
What is difference between compound and mixture / Give example .
Answer: 204
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Compound :
1:It is formed by chemical combination of atoms of element
2:Its components lose their own properties and produce new substance that have entirely different properties
Question: 205
What do you mean by malleability?
Answer: 205
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Malleability is the property by virtue of which metals can be drawn into sheets.
Question: 206
Why densities of gases are less than liquids ?
Answer: 206
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Gases have low density than liquids and solids . It is due to light mass and more volume occupied by the gas molecules . Gas density is expressed in grams per dm3. Whereas liquid and solid densities are expressed in grams per cm3 i-e liquids and solids are 1000 time denser than gases
Question: 207
What type of attractive forces exist between HCL molecules ?
Answer: 207
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Dipole-dipole attractiveforces exist between HCL molecules.
Question: 208
State John Dalton's atomic theory .
Answer: 208
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Main points of John Dalton's atomic theory are given as follows
Question: 209
Define effusion . Give example .
Answer: 209
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Effusion : Effusion is defined as the escaping of gas molecules through tiny holes into a space with lesser pressure
Question: 210
Why does rate of diffusion increase with increase of temperature?
Answer: 210
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Diffusion increases by increasing temperature because at high temperature the in termolecular forces become weak due to high kinetic energy of the molecules
Question: 211
Calculate the formula mass of the sodium sulphate .
Answer: 211
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Formula mass of the sodium sulphate :
Na2so4 =2(23) +(32)+4(16)
=46+32+64
=142amu
Question: 212
What type of elements form metallic bond?
Answer: 212
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Metals form metallic bond
Question: 213
Does Kelvin scale show negative temperature?
Answer: 213
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No. Kelvin scale does not show a negative temperature
Question: 214
For an element Z = 92 A = 238 Calculate number of neutron in it
Answer: 214
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Atomic mass = No of protons + No of neutrons =A=238
No of protons Z = 92
No of neutrons =N=A-z
=238-92= 146
Question: 215
Define evaporation and give example ?
Answer: 215
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Evaporation: The conversion of liquid into vapours called evaporation .
Question: 216
Write down chemical formula of calcium phosphate and sodium chloride ..
Answer: 216
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Chemical formula of calcium phosphate and sodium chloride is as fellows :
Question: 217
Why dose ice float on water?
Answer: 217
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lCe float on water due to hydrogen bonding. The density of ice is 0.917gcm-3 at OT and of water is 1 gcm3 at 0°C. Due to this ice molecules expand and float on water
Question: 218
Why do ionic compounds conduct electricity in solution or molten form?
Answer: 218
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Ionic compounds are good conductor in solution and molten form due to the presence of free ions in them
Question: 219
Why does group 1 elements prefer to combine with group 17 elements.
Answer: 219
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The elements of Group-1 being metals have the tendency to lose their valence electrons forming positively charged ions. Whereas non-metals of Group-17 have the tendency to gain or accept electrons. They are electronegative elements with high electron affinities. If atoms belonging to these two different group, metals and non-metals, are allowed to react. chemical bond is formed
Question: 220
What id meant by atom and ion?
Answer: 220
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Atom
1- It is the smallest particle of an smallest particle of an element.
2- It is electricallyneutral
3- It can take part in a chemical reaction
Question: 221
Differentiate saturated and unsaturated solution
Answer: 221
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Saturated : A solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 222
Write the percentage of volume by weight of oxygen in atmosphere and oceans
Answer: 222
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In atmosphere oxygen is 21% while in oceans it is 86%
Question: 223
Whether the density of gases increase on cooling ?
Answer: 223
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The density of gases increasing by cooling because their volume decreases and molecules of gases came close to each other
Question: 224
Why are the rates of diffusion in liquids slower than that of gases?
Answer: 224
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In liquid molecules intermolecular forces are stronger than gases and there molecules are, closer to each other. Asa result rate of diffusion in liquids are slower than gases.
Question: 225
Why ionic compounds are easy soluble in water?
Answer: 225
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Water is polar compound while ionic compound dissolves and forms cation and anion . Cation makes force of attraction with negative pole of water , while anion with positive pole of water and dissolve in water
Question: 226
Calculate molecular mass of sulphuric acid .
Answer: 226
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Molecular mass of sulphuric acid H2SO4
=2(1)+(32)+4(16)
=98amu
Question: 227
Define the term allotropy ?
Answer: 227
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Allotropy: The existence of an element in more than one forms in same physical state is called allotropy.
Question: 228
Why the ionic compounds have high melting and boiling points?
Answer: 228
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Ionic compounds have high melting and boiling points. As ionic compounds are made up of positive and negative ions, there exist strong electrostatic forces of attraction between oppositely charged ions. So, a great amount of energy is required to break these forces
Question: 229
What is a plum pudding theory ?
Answer: 229
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Thomson put forth his plum pudding theory . He postulated that atoms were solid structure of positively charge with tiny negative particle stuck inside . It is like plum in a pudding
Question: 230
Define chemical formula and give one examples .
Answer: 230
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Definition : A chemical formula is the symbolic representation the elements in the compounds and the ratio of the elements to one another
Question: 231
Define element?
Answer: 231
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Eelement:
Eelement is define as the substance which is made up of atoms of the same type or a substance in which all the atoms have the same atomicnumber, e.g.
Sodium (Na) and Hydrogen (H) etc
Question: 232
Give the electronic configuration of carbon atom.
Answer: 232
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Atomic no. of carbon = Z= 6
No of electrons in carbon atom =Z=6
Electronic configuration of carbon atom=ls2.2s2,2p2
Question: 233
Why suspension does not form homogeneous mixture?
Answer: 233
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sn, Particles remain un dissolved and from a heterogeneous mixture. Particles settle down after some times.
Question: 234
Why the liquid molecules are mobile ?
Answer: 234
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Liquid molecule have less intermolecular forces as compared to solids , which are not able to stable molecules of liquid at a fixed points . That is why liquid molecules are mobile
Question: 235
Write the relation between empirical formula and molecular formula
Answer: 235
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There is a relationship betweenempirical formula and molecularformula which is given as:
Molecular formula= (empirical formula
Where n= 1, 2, 3,,,,,,
Question: 236
Write difference between homoatomic and heteroatomic molecules ?
Answer: 236
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Heteroatomic molecules:
The molecules consisting of different types of atoms are called heteroatomic molecules
Question: 237
Is the Boyle's law valid at very high temperature?
Answer: 237
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No. Boyle's law is not valid at very high temperature
Question: 238
Why metals are good conductor of electricity ?
Answer: 238
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Metals are good conductors of heat and electricity in solid and liquid state due to mobile electrons
Question: 239
Human body made up of how many elements ? Write their names .
Answer: 239
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Six elements constitute about 99% of our body mass , oxygen 65% , Carbon 18% , Hydrogen 10% , Nitrogen 3%, Calcium 1.5% and phosphorous 1.5% , Potassium , Sulphur , Magnesium and sodium constitute 0.8 % of our body mass . Wherease copper , zinc , chlorine , fluorine , iron , cobalt and magnesium constitute only 0.2% of our body mass
Question: 240
Define Electrochemistry.?
Answer: 240
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Electrochemistry is the branch of chemistry which deals with the relationship b-cl electricity and chemical reactions.
Question: 241
If repulsive forces dominate to attractive forces will a covalent bond form?
Answer: 241
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If the repulsive forces dominate to attractive forces the covalent will not be formed. The covalent bond formed only when the attractive forces dominates over the repulsive forces.
Question: 242
Write chemical formula of Aluminium sulphate and Calcium phosphate .
Answer: 242
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Aluminium sulphate: Al2(SO4)
Question: 243
What is meant by relative molecular mass?

Answer: 243
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Relative molecular mass:
The ratio of the average mass of one molecule of an element or compound to one twelfth of the mass of an atom of carbon- 12
Question: 244
What will happen if the pressure temperature is kept constant?
Answer: 244
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The volume of gas will decrease three times when its pressure raised up to three times as temperature.
Question: 245
Write any two properties of covalent compounds .
Answer: 245
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1: Properties of coordinate covalent compounds are similar to those of covalent compounds . They are unsoluble in water and don't ionize so make solution on solving in organic solvent
Question: 246
Give some examples of arsenic and silver .
Answer: 246
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Symbols of arsenic and silver are as following
Question: 247
What type of bond exists in ionic compound?
Answer: 247
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Ionic bond exists in ionic compound.
Question: 248
Which type of electron are responsible for holding the atoms together in metals ?
Answer: 248
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Nuclei of metal atoms appear submerged in sea of these free mobile electrons . These mobile electrons are responsible for holding the atoms of metals together forming a metallic bond
Question: 249
Describe difference between Rutherford's theory and Bohr's atomic theory .
Answer: 249
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Rutherford's atomic theory
1: It was based upon classical theory
2: Electrons revolve around the nucleus
3: Atoms should produce continuous spectrum
4: Atoms should collapse
Question: 250
What are meant by coordinate covalent compounds ?
Answer: 250
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1: Properties of coordinate covalent compounds are similar to those of covalent compounds . They are unsoluble in water , don't ionize so make solution on dissolving in organic solvent
Question: 251
Define relative atomicmass based on C-12 scale.

Answer: 251
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Relative Atomic Mass:
The relative atomic mass of an element is the average mass of atoms of the element as compare to 1/11th the mass of one atom of carbon 12 isotope
Question: 252
What is the reason for the difference between solutions, colloids and suspensions?
Answer: 252
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Particles of solutions are so small that they can't scattered the rays of light, thus do not show Tyndall effect.
Particles of colloids scatter the path of light rays thus emitting the beam of light i.e. exhibit the Tyndall effect.
Particles of suspension are so big that light is blocked and difficult to pass
Question: 253
Explain any two factors that effect the diffusion .
Answer: 253
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Factors effecting in diffusion :
1 :Size of molecules : Big sized molecules diffuse slowly
Question: 254
Write electronic configuration of Mg
Answer: 254
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Atomic number of Mg 12
Question: 255
What is difference between ion and free radical ?
Answer: 255
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Free radicals :
1: These are the atoms that have odd number of electrons . They do not have any charge
2: They can exists in solutions as well as in air
3: They may form in the presence of light
Question: 256
Why gases are compressible ?
Answer: 256
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Gases are highly compressible due to empty spaces between their molecules . When the gases are compressed , then molecules come closer to one another and occupy less volume than in uncompressed state
Question: 257
Write two properties of ionic compound .
Answer: 257
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1: Ionic compound are mostly crystalline solid
Question: 258
An element with A = 39 , Z = 19 .Calculate the number of electrons and protons in one atom of this element
Answer: 258
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Atomic mass of an element = A = 39
Atomic number of element = Z = 19
As we know that atomic number is the number of protons present in the nucleus of an atom so , proton and electron always equal in any atom , that's why ,
Number of protons =19
Number of electrons = 19
Question: 259
What is the nature of electrode used in electroplating of chromium?
Answer: 259
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The object to be electroplated acts as cathode while anode is made of antimonial-lead.
Question: 260
How mass number of same elements are different ?
Answer: 260
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Isotopes of an element have same number of protons and electrons but different number of neutrons . That's why isotopes of an element have different atomic masses . Although atomic number remains same
Question: 261
What is meant by malleability ?
Answer: 261
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Malleabilityis the property by virtue of which a metal can be drawn into sheets
Question: 262
Where does most of the mass of an atom exists ?
Answer: 262
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Most of the mass of an atom exists in its nucleus . The sum of masses of protons and neutrons is equal to atomic mas of an atom
Question: 263
Differentiate between solute and solvent ?
Answer: 263
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Solute : The component which is present in smaller quantity is called solute
e.g : Salt in water , salt in solute
Question: 264
Write four examples of mixture .
Answer: 264
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1: Air is a mixture of nitrogen , carbon dioxide , noble gasses and water vapours
Question: 265
Show the state of Dynamic equilibrium in liquid and vapours with the help of diagram .
Answer: 265
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From the open surface of a liquid , molecules evaporates and mix up with the air but when we close a system ,evaporated molecules start gathering over the liquid surface . Initially the vapours condense slowly to return to liquid . After sometimes condensation process increases and a stage reaches when the rate of evaporation becomes equal to rate of condensation . At that stage the number of molecules coming back (condensing) to liquid . This state is called Dynamic equilibrium
Question: 266
Why arc the densities of gases tower than that of liquids?
Answer: 266
266-861
Gases has e low density than liquids and solids. It is due to light mass and more volume occupied by the gas molecules.
Question: 267
Write electronic configuration of Boron .
Answer: 267
267-861
Atomic no of Boron 5
Question: 268
Write the simplest way to distinguish between solution and pure liquid .
Answer: 268
268-861
The simplest way to distinguish between a solution and a pure liquid is evaporation . The liquid which evaporates completely , leaving no residue , is a pure compound , while a liquid which leaves behind a residue on evaporation is solution
Question: 269
Briefly describe the mobility of gases.
Answer: 269
269-861
Gas molecules are always in state of continuous motion . They can move from one place to another because gas molecules have high kinetic energy . This continuous motion of gases is called mobility of gases
Question: 270
What is meant by mixture ? Give example.
Answer: 270
270-861
When two or more elements or compounds mix up physically without any fixed ratio they form a mixture
Question: 271
Why does evaporation increase with the increase of temperature?
Answer: 271
271-861
At high temperature, rate of evaporation is high because at high temperature kinetic energy of molecules increases. So, it is high that they over-come the intermolecular forces and evaporate rapidly. For example, water level in a container with hot water decreases earlier than that of a container with cold water.
Question: 272
What is atomic number of Sulphur ? Write down its electronic configuration .
Answer: 272
272-861
Atomic number of Sulphur IS 16 .
Question: 273
State whether allotropy is shown by elements or compounds or both ?
Answer: 273
273-861
Allotropy is only shown by elements . It is not a property of compounds
Question: 274
Who discovered proton and neutron ?
Answer: 274
274-861
Proton is discovered by Goldstein in 1886
Question: 275
Why volume of gas decreases with increase of pressure ?
Answer: 275
275-861
Volume of gas decreases with increase of pressure because of empty spaces between their molecules . When gases are compressed the molecules come closer to one another and occupy less volume as compared to the volume in uncompressed state .
Question: 276
What is solid-solid solution ? Give two examples .
Answer: 276
276-861
Alloy: When solid solvent and solid solute make solutions it is called solid-solid solution
Question: 277
Define Dynamic equilibrium ?
Answer: 277
277-861
When the rate of evaporation becomes equal to rate of condensation . At that stage the number of molecules evaporating will be equal to the number of molecules coming back (condensing) to liquid . This state is called Dynamic equilibrium
Question: 278
Write two significance of chemical formula .
Answer: 278
278-861
1: it indicates the mass of the compound in amu or grams


Question: 279
Why does a dipole develop in a molecule ?
Answer: 279
279-861
The unequal sharing of electrons between two different types of atoms make one end of molecule slightly positive and other end slightly negatively charged . As shared pair of electron is drawn towards more electronegative atom , it is partially negatively charged . The other end automatically becomes partially positively charged
Question: 280
Define molar solution and give example .
Answer: 280
280-861
When one mole of solute is solved on one dm3 of solvent in measuring flask then it is called one molar solution
Question: 281
What is diffusion ? Explain with example ?
Answer: 281
281-861
Diffusion is defined as spontaneous mixing up of molecules by random motion and collisions to form a homogeneous mixture
Question: 282
What is difference between cation and anion ?
Answer: 282
282-861
Cation: An atom or group of atoms having positive charge on it is called cation

Example : like Na , k
Question: 283
State Charles's law
Answer: 283
283-861
The volume of a given mass of a gas is directly proportional to the absolute temperature when pressure kept constant."
Question: 284
What is meant by colloid ?
Answer: 284
284-861
The solutions in which the solute particles are larger than those solute particles present in true solution but not large enough to be seen with naked eye are called colloid solution . They show tyndal effect
Question: 285
Write two properties of liquid state of matter
Answer: 285
285-861
1: Liquid have fixed volume but no fixed shape . It attains the shape of container in which it is kept
Question: 286
Write down the chemical formula of silicon dioxide and calcium chloride .
Answer: 286
286-861
Silicon dioxide SiO2
Question: 287
Define aqueous solution
Answer: 287
287-861
The solution which is formed by dissolving a substance in water is called an aqueous solution
Question: 288
Define triads and law of octaves .
Answer: 288
288-861
Triads : The group of three elements called triads . In these groups central and middle element had atomic mass average of the other two element
Question: 289
Define solution with example .
Answer: 289
289-861
A solution is a homogenous mixture of two or more substances . The boundaries of compounds can not be distinguished i-e solution exists as one phase
Question: 290
What is the difference between diffusion and effusion ?
Answer: 290
290-861
Diffusion: The spontaneous mixing of molecules by random motion and collision of gases form homogenous mixture is called diffusion
Question: 291
When a gas is allowed to expand, what will be its effect on its temperature?
Answer: 291
291-861
According to Charles' Law when gas is allowed to expand its temperature also increases.
Question: 292
Define standard atmosphere pressure and write its unit .
Answer: 292
292-861
The pressure exerted by a mercury column of 760mm at sea level called standard atmospheric pressure
Question: 293
Why do the colloids show tydnall effect ?
Answer: 293
293-861
Colloids shows tyndall effect because the particles of
” colloids scatter the path of light rays due to large size.
Question: 294
What is solid-liquid solution ? Explain with example .
Answer: 294
294-861
When a solid dissolves in liquid and form solution called solid-liquid solution . If sugar dissolve in water it will be called solid-liquid solution.
Question: 295
What do you mean by evaporation and how it is affected by surface area?
Answer: 295
295-861
Evaporation: The process changing of a liquid into a gas phase is called evaporation.
Surface Area:
Evaporation is a surface phenomenon. Greater is surface area. greater is evaporation and vice versa. For example, sometimes a saucer is used if tea is to cooled quickly. This is because evaporation from larger surface area if saucer is more than that from the small surface area of a as cup.
Question: 296
Why amorphous solids do not have sharp melting points while crystalline solids do have ?
Answer: 296
296-861
Amorphous means shapeless . Solids in which the particles are not regularly arranged or their regular shapes are destroyed are called amorphous solids . They do not have sharp melting points . While solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids . They have definite surface or faces . Each face has definite angle with other . They have sharp melting points
Question: 297
Define atomic mass unit .
Answer: 297
297-861
One atomic mass unit is 1/12th of the ,ass of one atom of carbon 12 . When this atomic mass unit is expressed in gram , it is 1amu = 1.66*10-24 g
Question: 298
Define relative atomic mass.
Answer: 298
298-861
Relative atomic mass of an element is the average mass of an atom of that element as compared to 1/12th the mass of atom of carbon-12 isotopes
Question: 299
What is compressibility?
Answer: 299
299-861
Decrease of volume by increasing pressure is called compressibility of that thing like gases . Gases are highly compressible due to empty spaces between their molecules
Question: 300
Can, you cool a gas by increasing its volume
Answer: 300
300-861
No. we cannot cool a gas by increasing its volume
Question: 301
How much amount of KOH required to form 1 molar solution ?
Answer: 301
301-861
Concentration of solution = 1dm3
Molar mass of KOH = 39+16+1
= 56 mol
Question: 302
What is difference between group and period ?
Answer: 302
302-861
Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
Question: 303
how can you explain the solute-solvent interaction to prepare NaCI Solution?
Answer: 303
303-861
When NaCI is added in water it dissolves readily because the attractive interaction between the ions of NaCI and polar molecules of water are strong enough to overcome the attractive forces between Na' and CI- ions in solid NaC1 crystal. In this process the positive end of the water dipole is oriented towards the CF ions and the negative end of water dipole is orwater molecules are so strong that they pull these ions from their positions in the the Na- ions. These ion dipole attractions between Na+ ions and water molecules, Cl- ions and water molecules are so strong that they pull these ions from their positions in the crystal and thus NaCl dissloves
Question: 304
What is meant by ion ? Give example .
Answer: 304
304-861
Ion is an atom or group of atoms having a charge on it .
Question: 305
What is transition temperature of sulphur?
Answer: 305
305-861
Its transition temperature is 96.
Question: 306
What is meant by true solution ?
Answer: 306
306-861
True solution are the homogeneous mixture of two or more than two components . Each components is mixed in such a way that their individual identity is not visible
Question: 307
Write down the chemical formulas of the following
(a) Sugar (b) Sulphuric acid
Answer: 307
307-861
(a) Sugar : C12H22O11
Question: 308
Differentiate between molecular mass and formula mass .
Answer: 308
308-861
Formula mass:
1:The sum of atomic masses of all the atoms present in one formula unit of a substance is called formula mass
2:Formula mass is related to ionic compound
Examples : NaCl = 23+36.5= 58.5 amu
Question: 309
In electroplating of silver, from where Ag+ ions come and where they deposit?
Answer: 309
309-861
In electroplating of silver in the cell, the anode dissolves to produce Ag+ ions, that towards the cathode. At cathode they're discharged and deposited on the object e.g. spoon. chemical reaction can be represented as:
Question: 310
Explain Dobereiner's triads .
Answer: 310
310-861
Dobereiner observed relationship between atomic masses of several groups of three elements called triads . In these groups , the central or middle element had atomic mass average of the other two elements
Question: 311
Calculate molecular mass of NH3.
Answer: 311
311-861
Molecular mass :
NH3 =14+1*3
=17a.m.u
Question: 312
What is absolute zero?
Answer: 312
312-861
It is the temperature at which an ideal gas would have zero volume.
Question: 313
Describe the number of molecules in 9 g water.
Answer: 313
313-861
Volume of water = 9g
Question: 314
What is absolute temperature scale?
Answer: 314
314-861
Lord Kelvin introduced absolute temperature scale or Kelvin scale • This scale of temperature starts from OK or -273.15°C which is given the name of absolute zero.
Question: 315
Why does true solutions not show Tyndall effects?
Answer: 315
315-861
True solutions not show Tyndall effectsbecause particle are so small that they can not scatter the the rays of light, thus do
not show tyndall effect.
Question: 316
Define noble gases and give example .
Answer: 316
316-861
Elements of group 18 are called Noble gases
All noble gases have completely filled outermost shells . This is because of this reason , they do not sow any chemical reactivity . They are chemically inert
Question: 317
What are two defects in Rutherford's atomic model ?
Answer: 317
317-861
1: According to classical theory of radiation , electrons being the charged particles should release or emit energy continuously and they should ultimately fall into the nucleus
Question: 318
If 16g of oxygen contains 1 mole of oxygen atom, calculate the mass of one atom of oxygen in grams .
Answer: 318
318-861
No of atoms in one mole =6.02×1023
Question: 319
Which of the following will scatter light and why?
Sugar solution, Soap solution, Milk of magnesia.
Answer: 319
319-861
Soap solution is colloidal solution and have particles large enough to scatter the light
Question: 320
Write down the electronic configuration of following
1: Na 2: Al
Answer: 320
320-861
1: Atomic number of Na 11
11Na = 1s2. 2s2 . 2p6 . 3s1
Question: 321
What is kept constant in Charles law ?
Answer: 321
321-861
Pressure is kept constant in Charles law
Question: 322
Write chemical formula of caustic soda and washing soda .
Answer: 322
322-861
Caustic soda: NaOH
Question: 323
Write the chemical formula of water and sugar.
Answer: 323
323-861
Water :C12H22O11
Question: 324
Why is melting point of a solid considered its 'identification' characteristics ?
Answer: 324
324-861
The melting point of a solid considered its identification because pure solids have a sharp and specific melting point , no other solid has same melting point
Question: 325
Why elements are called s and p block elements ?
Answer: 325
325-861
Elements are called s and p block elementsbecause their last element is present in s and p sub shell
Question: 326
Convert -30°C to K unit
Answer: 326
326-861
As we know that
(T)k = (T)°C +273
By putting°C=-30°
(T)k = (-30)°C +273
(T)k = (-30+273)°C
(T)k = 243°C


Question: 327
Define avagadro's number
Answer: 327
327-861
Avagadro's number is a collection of6.02 × 1023 particles. It is represented by symbol 'NA'. Hence the6.02 × 1023 number of atoms , molecules or formula unit is called avagadro's number that is equal to 1 mole of respective substance
Question: 328
Write down electronic configuration of sodium .
Answer: 328
328-861
Electronic configuration of sodium
11Na = 1s2 , 2s2 , 2p6 , 3s1
Question: 329
Is sign of (0) used on Kelvin?
Answer: 329
329-861
No. Degree sign (°) is used with Celsius scale not with Kelvin scale.
Question: 330
Which variables are kept constant in Charles' law?
Answer: 330
330-861
Pressure is kept constant in Charles' law
Question: 331
Define formula mass and formula unit .
Answer: 331
331-861
Formula unit : formula unit is defined as the simplest whole number ratio of ions ,as present in the ionic compounds
Question: 332
What is absolute temperature scale ?
Answer: 332
332-861
Lord kelvin introduced obsolute temperature scale or kelvin scale . The scale of temperature starts from 0K or -273.15°Cwhich is given as a name of absolute zero . It is the temperature at which an ideal gas would have zero volume
Question: 333
Write symbol of any four elements of halogen .
Answer: 333
333-861
1: Flourine (F)
Question: 334
Why suspensions and solutions do not show Tyndall effect , while colloids do ?
Answer: 334
334-861
Suspensions and solutions do not show Tyndall effect because particles of solution are so small that can't be scatter the rays of light and particles of suspension are so big that light is blocked and difficult to pass . The colloids do show Tyndall effect because particles scatter the path of light rays thus emitting the beam of light i-e exhibit the Tyndall effect
Question: 335
What is meant by molecular ion ?
Answer: 335
335-861
When a molecule loses or gains one or more electron , it forms a molecular ion

Question: 336
Why is galvanizing done?
Answer: 336
336-861
The process of coating a thin layer of zinc or iron is called galvanizing. Galvanizing is dot, because zinc protects the iron against corrosion even after the coating surface is broken.
Question: 337
Define effective nuclear charge .
Answer: 337
337-861
In an atom , attraction of outer most electrons around the nucleus is decreased due to inner electrons . In result , an atom faces less nucleus charge then the original
Question: 338
Define shielding effect , Describe its trend in a period
Answer: 338
338-861
Shielding effect : The force of attraction between the nucleus and valence electrons is reduced due to the presence of internal - shell electrons (core electrons ) This is called shielding effect
Question: 339
How free radical is formed ?
Answer: 339
339-861
Free radicals are formed by the homolytic (equal) breakage of bond between two atoms when they absorb heat or light energy
Question: 340
Differentiate between boiling and melting point .
Answer: 340
340-861
Melting point : The temperature at which the solid starts melting and exist in dynamic equilibrium with liquid state is called melting point
Question: 341
Convert the following. Ans: a) 70 cm lig to atm. b) 3.50atm to torr. c) 1.5 atm to Pa.
Answer: 341
341-861
70 cm Hg to atm
We know that
76 cm 11g= 1 atm
1 em = 1/76 atm
70 cm Hg = 1/76. 70atm
70 cm lig =0.92 atm

Question: 342
How meat can be preserved ?
Answer: 342
342-861
Table salt is the most important ingredient for curing meat and is used in large quantities . Salt kills and inhibits the growth of putrefying bacteria by drawing water out of the meat . Concentrations of salt up to 20% are required to kill most of the species of unwanted bacteria . Once properly salted , the meat contains enough salt to prevent the growth of many undesirable microbes
Question: 343
What is meant by condensation ?
Answer: 343
343-861
The returns of the vapours into liquids state on cooling is called condensation
Question: 344
Why is vapour pressure higher at high temperature?
Answer: 344
344-861
At high temperature, vapour pressure is higher than at low temperature. At elevated temperature, the Kinetic energy of the molecules increases enough to enable them to vaporize and exert pressure.
Question: 345
Write the redox reaction taking place during the electroplating of chromium.
Answer: 345
345-861
Reaction at the electrodes are as Follows:
At anode 40H-2H2O+O2+4e-
At cathode C+33e-Cr
Question: 346
Describe difference between concentrated and dilute solution .
Answer: 346
346-861
Concentrated solution : The solution which contains relatively large amount of dissolved solute in solution is called concentrated solution
Question: 347
Wrote the observations made by Rutherford .
Answer: 347
347-861
Observations made by Rutherford are as follows :
Question: 348
Why we stir paint thoroughly before using?
Answer: 348
348-861
We stir paints thoroughly before using because paints is suspension and suspension is heterogeneous mixture of un- dissolved particles which can be seen with naked eye and settle down alter sometime. We stir paints thoroughly so that particles suspend again
Question: 349
How much NaOH is required to prepare its 500cm3 of 0.4m solution?
Answer: 349
349-861
Molar mass of NaOH =40gmol-3
Question: 350
Differentiate between gram atomic mass and gram molecular mass .
Answer: 350
350-861
Gram atomic mass: The atomic mass of an element expressed in grams . It is called gram atomic mass
Question: 351
In which units body temperature is measured ?
Answer: 351
351-861
Body temperature is measured in Fahrenheit scales . Normal body temperature is 98.6°F , it is equivalent to 37° C . This temperature is close to average normal atmospheric temperature
Question: 352
How many electrons will be in M shell of an atom having atomic no 15?
Answer: 352
352-861
Atomic number 15
K shall = 2 electrons
L shall = 8 electrons
M shall = 5 electrons
Question: 353
Describe exothermic reaction with example .
Answer: 353
353-861
Exothermic reaction are those reactions in which heat is released. In theses reactions test tubes becomes hot . Aqueous solution of calcium oxide (CaO) , lithium sulphate Li2SO4and cerium sulphate Ce2(SO4) are examples of exothermic reactions
Question: 354
Define Boyle's law .
Answer: 354
354-861
According to Boyle's law the volume of a given mass of a gas is inversely proportional to its pressure at constant temperature .
Question: 355
Why volume of a gas decreases with increase of pressure"
Answer: 355
355-861
The volume of a given mass of a gas is inversely proportional to the pressure if the temperature is kept constant' therefore while decreasing the volume of gas pressure will increase
Question: 356
Can colloids he separated by filtration, if not why?
Answer: 356
356-861
Colloids cannot be separated by filtration because particles are big but they can pass through a filter paper.
Question: 357
Write down the electronic configuration of fluorine and Neon
Answer: 357
357-861
Electronic configuration of fluorine:
9F=1s2 , 2s2 , 2p4
Question: 358
What is the difference between the evaporation and boiling point ?
Answer: 358
358-861
Evaporation : The process of changing of a liquid into a gas phase is called evaporation .
Question: 359
Give the reason for the decrease of electronegatively in down the group .
Answer: 359
359-861
Electronegatively decreases down a group because size of the atom increases . The attraction for the shared pair of electrons weakens
Question: 360
For what purpose P-32 and Sr - 90 are used .
Answer: 360
360-861
1: For the treatment of skin cancer , isotopes like P-32 and Sr-90 are used because they emit less penetrating beta radiations
Question: 361
Calculate the formulas mass of potassium sulphate
Answer: 361
361-861
Formulas mass of potassium sulphate (K2SO4)
K2SO4 = 2(39)+(32)+4(16)
= 78+32+64
= 174a.m.u
Question: 362
Define solution ?
Answer: 362
362-861
A solution is homogenous mixture of two or more substances
Question: 363
Define transition temperature . Give example .
Answer: 363
363-861
The temperature at which one allotropes changes into another is called is called transition temperature
Question: 364
Why does evaporation increases with the increase in temperature ?
Answer: 364
364-861
Evaporation increase with the increase of temperature because at high temperature K.E of the molecules increase so high that they overcome the intermolecular forces and evaporate rapidly
Question: 365
Why the trend of electron affinity and electron -negativity same in the period?
Answer: 365
365-861
The electron -negativity and electron affinity , both depends upon the size of atom and the nuclear charge . In the period from left to right the nuclear size decreases and nuclear charge increases . Therefore the trend of both is same
Question: 366
Which allotropic form of carbon is stable at room temperature (25°C)?
Answer: 366
366-861
Graphite is more stable at room temperature
Question: 367
Define pascal .It is the unit of which quantity ?
Answer: 367
367-861
If one newton force is applied on 1m2area then pressure is called one pascal . It is unit of pressure
Question: 368
Define Bond pair ?
Answer: 368
368-861
The valence electrons which take part in covalent bond is called bonding electrons . These electrons present in the incomplete valence shell
Question: 369
Write two difference between atom and anion
Answer: 369
369-861
Ion :
1: It is the simplest unit of ionic compound
2: It has net charge either negative or positive on it
Question: 370
An element X has oxidation state 0 . What will be the oxidation state when it gains three electrons ?
Answer: 370
370-861
Suppose the element x
X0 +3e- X-3
Question: 371
What is tyndall effect ? On which factor it depends ?
Answer: 371
371-861
Tydnall effect: The particles of colloids are big enough to scatter the beam of light . It is called tydnall effect
Question: 372
Why does covalent bond become polar?
Answer: 372
372-861
If the covalent bond is formed between two different atoms bond pair of electrons will not attracted equally by the bonded atoms . The atom which has greater electronegativity will attract bond pair more towards itself than other atom and hence molecule will become polar
Question: 373
Why does chlorine accept an electron and attain -1 charge ?
Answer: 373
373-861
Chlorine have seven electrons in its valence shell . It require one electron to complete its valence shell . That's why chlorine accept an electron and attain -1 charge
Question: 374
Molecular formula of a sulphur molecule
Answer: 374
374-861
The Molecular formula of a sulphur molecule S8
Question: 375
Calculate the gram molecule in 40g of phosphoric acid
Answer: 375
375-861
Molar mass of phosphoric acid H3PO4 = 3+31+64=98
Question: 376
Define super-saturated solution .
Answer: 376
376-861
The solution that is more concentrated than a saturated solution at a given temperature is known as super- saturated solution
Question: 377
Justify with an example the solubility of salt increases with increase in temperature?
Answer: 377
377-861
When salts like KNO3, KCl are added in water, the test tube become cold. It means during dissolution of this salts heat is absorbed. Such dissolving process in called endothermic Solvent + Solute + Heat-+Solution Solubility increase with the increase in temperature. It means that heat is required to break attractive forces b/w the ions of solute. This requirement is fulfilled by surrounding molecules.
Question: 378
Write short note on discovery of Neutron.
Answer: 378
378-861
Chadwick discovered Neutrons in 1932 . He bombarded alpha particles on Beryllium . He observed that the radiation of very high penetrating power were produced ( They can move through long distance in air ) .These radiations were called Neutron
Question: 379
In which unit body temperature is measured ?
Answer: 379
379-861
Body temperature is measured in fahrenheit scale
Question: 380
How cation and anion is formed ?
Answer: 380
380-861
Cation is formed by the loss of one or more electrons
Question: 381
What is the percentage m/volume ?
Answer: 381
381-861
It is the number of grams of solute dissolved in 100cm3of solution
Question: 382
How molar solution is prepared ?
Answer: 382
382-861
One molar solution is prepared by dissolving 1 mole of the solute in sufficient water to make the total volume of solution upto 1 dm3 in a measuring flask
Question: 383
Calculate the number of mole carbon in 84 gram of carbon .
Answer: 383
383-861
Mass of C = 84 gm
Molecular mass of C = 12 gm
Quantity of moles = 84/12
= 7 moles
Question: 384
How many blocks are present in periodic table ?
Answer: 384
384-861
There are4 presentin periodic table called s, p, d and f block
Question: 385
Why test tube becomes cold when KNO3 is dissolved in water ?
Answer: 385
385-861
The dissolution of KNO3 in water is an endothermic process in which heat absorbed when KNO3 dissolve in test tube it becomes cold
Question: 386
Convert -45°C to kelvin temperature .
Answer: 386
386-861
(T)K = (T)°C +273
(T)K = (-45)°C +273
(T)K = (-45+ 273)°C
(T)K = 228

Question: 387
Explain the law of flow of heat ?
Answer: 387
387-861
In winter atmospheric temperature falls lower than that of our body temperature . According to principle of heat flow out from our body and we feel cold . To control this outward flow of heat , we wear black and warm clothes . To maintain body temperature we use dry fruits tea, coffee and meats etc
Question: 388
What is redox reaction ?
Answer: 388
388-861
The reaction in which simultaneously oxidation and reduction takes place is called redox reaction
Question: 389
Differentiate between polar and non polar covalent bond .
Answer: 389
389-861
Polar covalent bond : Covalent bond is formed between different atoms having different electronegativity between bonded atoms . Due to which one atom get negative and other get positive charge
Question: 390
Why drops of rain fall downward?
Answer: 390
390-861
The density of liquid depends upon its mass and volume . Liquids are denser than gases because molecules of liquid are closely packed and the space between their molecules are negligible . As the liquid molecules have strong intermolecular forces hence they cannot expand freely and have a fixed volume . Like gases they cannot occupy all the available volume of the container that is the reason why densities of liquid are high
Question: 391
What is the relationship between electro positivity and ionization energy ?
Answer: 391
391-861
Electronegativity depends upon the ionization energy which is in turn depends upon size and nuclear charge of the atom
Question: 392
Why nitrogen forms compounds with alkaline earth metals directly ?
Answer: 392
392-861
A alkaline earth metals from stable nitrides when heated with nitrogen
Question: 393
An element has 5 electrons in M shell . Find its atomic number
Answer: 393
393-861
The element has 5 electrons in M shell has atomic number 15 and name of element is phosphorous
Question: 394
Write two difference between molecule and molecular ions .
Answer: 394
394-861
Molecule :
1: molecule is formed by the combination of two or more atoms . Which can exist independently and shows all the properties of that compound i.e CO2, CH4 etc
2: It is always neutral
3: It is formed by the combination of atoms
4: It is stable unit
Question: 395
How does nature of attractive forces of solute-solute solvent -solvent affect the solubility?
Answer: 395
395-861
Solutions formation depends upon the relative strength of attractive forces between solute - solute , solvent-solvent and solute-solvent . Generally solutes are solids , ionic solids are arranged in such a regular pattern that the inter ionic forces are at a maximum . If the new forces between solute and solvent particles overcome the solute-solvent attractive forces , then solute dissolves and make a solution . If the forces between solute particles are strong enough then solute-solute forces , solute remains insoluble and solution is not formed
Question: 396
Why Lanthanides an Actanides are placed separately below periodic table . Explain
Answer: 396
396-861
Because of space problem in periodic table two series of elements were placed separately below the normal periodic table to keep it in a manageable and presentable form . Since the two series start after Lanthanum (z=57) and Actinum (z=89) , so these two series of elements are named as Lanthanides and Actanides
Question: 397
Name a metal which exists in liquid form? Ans: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state
Answer: 397
397-861
All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state
Question: 398
Why the ionization energy of Na is more than K?
Answer: 398
398-861
Ionization energy of sodium is more than K because down the group electropositive character increases and ionization energy decreases. As it become easier to remove electron' down the group
Question: 399
Define m0ole and give example .
Answer: 399
399-861
Atomic mass , molecular mass or formula mass of a substance expressed in grams is called a mole
Question: 400
What do you mean like dissolve like ? Explain with example ?
Answer: 400
400-861
The general principle of solubility is , like dissolve like
1: The ionic and polar substance are soluble in polar solvents . ionic solids and polar covalent compounds are soluble in water e.g KCl , Na2CO3, CuSO4etc
Question: 401
In electroplating of chromium which salts is used as an electrolyte?
Answer: 401
401-861
In electroplating of chromium, Cr2(SO4)3, is used as an electrolyte.
Question: 402
For what purpose , Iodine-131 is used ?
Answer: 402
402-861
Isotopes of iodine I-131 is used to diagnose goiter in thyroid
Question: 403
What is charles law ? Write its equation .
Answer: 403
403-861
French scientist J.Charles in 1787 , presented his law that states the volume of given mass of a gas is directly proportional to the absolute temperature if the pressure is kept constant
Question: 404
How many atoms of hydrogen present in one mole of water ?
Answer: 404
404-861
One molecule of water is made up of two atoms of hydrogen and 1 atom of oxygen , hence 2×6.02×1023.atoms of hydrogen and6.02×1023 atoms of oxygen constitute one mole of water
Question: 405
Why an iron grill is painted frequently?
Answer: 405
405-861
Iron grill is painted frequently because due to presence of oxygen and water in air. It become, corrode. So to prevent it front rusting it is painted
Question: 406
Describe difference between true solution and colloid .
Answer: 406
406-861
True solution : True solutions are the mixture of homogenous mixture of two or more than two components . Each component is mixed in such a way that their individual identity not visible
Question: 407
Write two / four characteristics of cathode rays.
Answer: 407
407-861
1: Cathode rays travel perpendicular to the cathode surface
Question: 408
Differentiate between oxidation and reduction.
Answer: 408
408-861
Oxidation : Oxidation is defined as addition of oxygen or removal of hydrogen during a chemical reaction
e.g
ZnO + CZn +CO2
Question: 409
Write electronic configuration of Aluminuim .
Answer: 409
409-861
Atomic number of Aluminium is 13
13Al = 1s2 , 2s2, 2p6, 3s2, 3p1
Question: 410
What do you mean by %volume/volume
Answer: 410
410-861
It is a volume in cm3 of a solute dissolved. per100cm3 of solution. For example 3O% alcohol solution means 30cm3 of alcohol dissolved in sufficient amount of water, so total volume would 100 cm3
Question: 411
What is vapour pressure ?
Answer: 411
411-861
The pressure exerted by the vapour of a liquid at equilibrium with the liquid at a particular temperature is called vapour pressure of liquid
Question: 412
Name the by-products produced in Nelson's Cell?
Answer: 412
412-861
The chlorine and hydrogen gas are produce as by product in Nelson's Cell
Question: 413
Why valence of chlorine is 1 ?
Answer: 413
413-861
The valency of chlorine is 1 and charge is negative because chlorine belongs to 17th group of periodic table . Its electronic configuration is Cl17=1s2,2s2,2p6,3s2,3p5the valence shell of chlorine deficient by one electron . So, it accepts one electron from any metal and gets 1 charge
Question: 414
Describe trend of shielding effect in periodic table .
Answer: 414
414-861
The shielding effect increase down the group in the periodic table . Because of this it is easy to take away electron in potassium (Z=19) than from sodium (Z=11) atoms . Similarly the shielding effect decrease in a period if we move from left to right
Question: 415
An element in oxidation state +7 gains electrons to be reduced to oxidation state +2 . How
Answer: 415
415-861
Suppose an element X +7

Question: 416
Is the Boyle's law applicable to liquid ? Give reason .
Answer: 416
416-861
No we can not apply Boyle's law to liquid because in them intermolecular distance is very less and they are highly incompressible so the effect of pressure does'nt effect much on liquids . That's why we can not apply Boyle's law to liquids
Question: 417
Convert 560 torr into cmHg
Answer: 417
417-861
1 torr = 1mm Hg
Question: 418
iodine exists in solid state, can it be beaten with hammer to form sheets?
Answer: 418
418-861
No, only solid metals have the characteristic to be beaten with hammer to for sheet
Question: 419
Why does evaporation cause cooling ?
Answer: 419
419-861
When the high kinetic energy molecules evaporates from the surface of liquid , the temperature of the remaining molecules falls down . To compensate the energy decrease , the molecules absorb heat from surrounding falls down and we feel cooling
Question: 420
Write down the name of particles which determine the mass of an electron .
Answer: 420
420-861
The proton and neutron determine the mass of an atom
Question: 421
What would be the number of moles in 9.0 gram carbon ?
Answer: 421
421-861
Number of moles of carbon = 9 g
Molar mass of carbon = 12 g
Number of moles = ?

Question: 422
What is meant quantum ?
Answer: 422
422-861
Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation . Quanta is plural of quantum . In 1918 , Noble prize in physics was awarded to German physicist Max Planck ( 1858-1947) for work on the quantum theory
Question: 423
Difference between oxidation state and valency
Answer: 423
423-861
Oxidation : Oxidation state is apparent charged assign to an atom of an element in a molecule or an ion .
While assigning O.S the sign precedes the number
e.g +2
Question: 424
Why alkali metals are more reactive than alkaline earth metals ?
Answer: 424
424-861
Alkali metals are extremely reactive because of their ns1valence shell electronic configuration . As there is only one electron in their valence shell , it can be easily given out . It is the reason that they are always found in in nature as cations with +1oxidation state . Therefore , they readily form salts with non-metals
Question: 425
What are the elements arranged in group 3 to 12 called ?
Answer: 425
425-861
The groups 3 to 12 are called transition elements . In these elements 'd ' sub shell is in the process completion
Question: 426
Define oxidation and give example .
Answer: 426
426-861
Oxidation reaction : The loss of electron by an atom or ion is called oxidation .
Question: 427
Give application of silver ?
Answer: 427
427-861
1: Compound of silver are widely used in photographic films
Question: 428
Convert 30°Cto kelvin temperature
Answer: 428
428-861
We know that
(T)K = (T)°C +273
by putting the values of C°=30° we have
(T)K = (30)°C +273
(T)K = (30+273)°C
(T)K = 303


Question: 429
Why do electrodes get their names "anode" and cathode in galvanic cell?
Answer: 429
429-861
In galvanic, cell. Oxidation take place at anode while reduction take place at cathode
Question: 430
Define oxidation in terms of electrons and give an example .
Answer: 430
430-861
Oxidation : The loss of electron by an atom or ion is called oxidation
Question: 431
Write example of use of radioactive isotopes in the field of medicine and radiotherapy
Answer: 431
431-861
In the field of medicine isotopes of iodine I -131 are used for diagnosis of goiter in thyroid gland . While P-32 and Sr 90 are used in the field of radioactivity
Question: 432
Write two properties of crystalline solids .
Answer: 432
432-861
1: In crystalline solids particles are arranged in definite in definite pattern .
Question: 433
Write properties of Neutrons .
Answer: 433
433-861
Properties of neutrons particles are given below :
Question: 434
Why is 02 necessary for rusting?
Answer: 434
434-861
02 is necessary for rusting because it acts as oxidizing agent. It first oxidize iron-to Fe+2 ion thus Fe+ ion to rust (Fe203.n H2O) in the presence of water.
Question: 435
What is difference between electron affinity and electron -negativity ?
Answer: 435
435-861
Electron affinity : Energy emitted due to the absorption of an electron in gaseous atom of an element is called electron affinity .
Question: 436
Write formulas of two ionic compounds which are soluble in water .
Answer: 436
436-861
The two ionic compound which are soluble in water are following
Question: 437
Define electrochemical cell . With the names of its types .
Answer: 437
437-861
Electrochemical cell is an energy storage device in which either a chemical reaction takes place by using electric current or chemical reaction produces electric current
Question: 438
Write two uses of redox reaction .
Answer: 438
438-861
Redox reaction are useful in batteries to produce energy and this electricity is used to drive non-spontaneous reaction
Question: 439
What are two factors on which evaporation depends ?
Answer: 439
439-861
Surface area : Evaporation is a surface phenomenon . Greater is surface area greater is evaporation
Question: 440
Anode of downs cell is made up of non metal , what is its name ?
Answer: 440
440-861
Anode of down cell is made of non-metal , Its name is graphite . The Cl- ions are oxidized to give Cl2 gas at anode
Question: 441
What is the nature of charge on cathode ray ?
Answer: 441
441-861
Cathode rays are deflected toward positive plate in an electric field showing that they are negatively charged
Question: 442
Write the name of two non-polar solvents .
Answer: 442
442-861
Toluene and benzene aretwo non-polar solvents
Question: 443
What is maximum capacity of a metal ?
Answer: 443
443-861
1: K shall can accommodate 2 electrons
Question: 444
Define oxidation state ?
Answer: 444
444-861
Oxidation state is the apparent charge assigned to an atom of an element in a molecule or ion
Question: 445
Why benzene is insoluble in water ?
Answer: 445
445-861
The principle of solubility is 'like dissolve like' . Benzene is a non-polar compound whereas water is a polar compound . Due to the reason , benzene is insoluble in water
Question: 446
Why are the colloids quite stable ?
Answer: 446
446-861
In colloid particles are large but not large enough and they are stabilized hence they do not settle down for a ling time that is why colloids are quite stable
Question: 447
What do you know about the construction of an electrolytic cell?
Answer: 447
447-861
An electrolytic cell consists of solution of an electrolyte two electrodes (anode, cathode)that are dipped in the electrolytic solution and connected to the battery . The electrode connected to positive terminal is called anode and electrode connected to the negative terminal is called cathode
Question: 448
Write electronic configuration of chlorine and carbon
Answer: 448
448-861
Electronic configuration of carbon : 12 C 6 = 1s2 , 2s2 , 2p2
Question: 449
Why suspension and solutions do not show Tyndnall effect , while colloids do?
Answer: 449
449-861
Solution does not show Tyndall effect because their particles are so small that they cannot scatter the ray of light . Suspensions do not show Tyndall effect because their particles are so big that light is blocked and difficult to pass . Colloid shows Tyndall effect because their particles are big enough to scatter the beam of light
Question: 450
What is by-products are produced in Down's cell?
Answer: 450
450-861
Chlorine is produce in the downs cell as a by product
Question: 451
Define electrolysis and give example .
Answer: 451
451-861
The decomposition of compound by passing electric current through molton or aqueous solution of the compound called electrolysis
Question: 452
Describe two characteristics of canal rays .
Answer: 452
452-861
1: Canal rays travel in straight line in direction opposite to the cathode rays and cast a sharp shadow of an opaque object if placed in their path
Question: 453
Where sodium metal is obtained from fused sodium chloride .
Answer: 453
453-861
Sodium metal accumulates at iron cathode in down's cell
Question: 454
What is difference between short period and ling period ?
Answer: 454
454-861
Short period : First period of periodic table is called short period . It consists of Hydrogen and Helium
Question: 455
Why does sodium form a chemical bond with chlorine ?
Answer: 455
455-861
Sodium become Na by losing an electron and eight electrons remains in its valence shell . Chlorine gain an electron and becomes Cl-ion . Both these ions attract each other and become stable
Question: 456
Write down the two postulates of Bohr's atomic model .
Answer: 456
456-861
1: The hydrogen atom consists of a tiny nucleus and electrons are revolving in one of circular orbits of radius ' r ' around the nucleus
Question: 457
Write down the number and names of subshell in N-shell .
Answer: 457
457-861
Number of sub shell in N shell is 4 named as s ,p ,d and f
Question: 458
How does electron differ from a neutron ?
Answer: 458
458-861
Electron
1: Electrons have negative charge
2: The mass of the electron is 1940 times less than proton
Question: 459
Write down electronic configuration of phosphorous .
Answer: 459
459-861
Atomic number of phosphorous is 15 Electronic configuration is given as below :
Question: 460
What is the affect of temperature on vapour pressure ?
Answer: 460
460-861
By increasing temperature , vapour pressure increases and by decreasing temperature vapour pressure decreases
Question: 461
What are cathode rays ? Who discovered it?
Answer: 461
461-861
In 1897 JJ Thomson discovered cathode rays
Question: 462
For what purpose C-14 is used ?
Answer: 462
462-861
Uses of C-14
Question: 463
Write the names of two allotropic forms of sulphur .
Answer: 463
463-861
The allotropic forms of sulphur are given below :
Question: 464
How is the periodicity of properties depends upon the number of proton in an atom ?
Answer: 464
464-861
Periodicity of properties depends upon the atomic number . Atomic number is defined as total number of protons and nutron in a nucleus of any atom . That's the reason periodicity of properties depend upon protons
Question: 465
Write down use of paints and greases .
Answer: 465
465-861
1: Greasing or painting of the surface can prevent the corrosion of iron
Question: 466
Why does Aluminium not rust ? Explain
Answer: 466
466-861
Aluminium corrodes but it does not rust because a very hard material aluminium oxide , protects the aluminium from rust and further corrosion . Rust refers only to iron and steel corrosion . Whenever , iron corrodes its colour changes that exposes iron to further rusting
Question: 467
Define unsaturated solution .
Answer: 467
467-861
The solution which have capacity to dissolve more amount of solute is called unsaturated solution
Question: 468
Define melting point ?
Answer: 468
468-861
The temperature at which the solid starts melting and exists in dynamic equilibrium with liquid state is called melting point
Question: 469
Define electronic configuration . Also give example .
Answer: 469
469-861
The distribution of electrons around the nucleus in various shells and sub shells according to their increasing energy is called electronic configuration.
Question: 470
What is difference between solution and mixture ?
Answer: 470
470-861
Solution : Homogenous mixture of two or more substance called solution
Question: 471
Why shielding effect of electron makes cation formation easy ?
Answer: 471
471-861
Shielding effect reduce the effective nuclear charge due to the nucleus thus the net force on the valence electrons decrease due to higher shielding effect . That is why the removal of valence electron become easy for cation formation
Question: 472
Why is the formula of solute necessary for calculation of the molarity of the solution ?
Answer: 472
472-861
Formula of solute is necessary for calculation of the molarity of the solution because molarity depends upon No. of moles of solute
Question: 473
Why is HF a weak acid ?
Answer: 473
473-861
HF less ionizes , hydrogen bond is present between its molecules . That is why it is a weak acid
Question: 474
What type of solutions butter and smoke are ?
Answer: 474
474-861
Solution : Butter , smoke
Question: 475
Why the boiling point of water higher than alcohol?
Answer: 475
475-861
Water has ability to form two hydrogen bonds while Ethyle alcohol has ability to form one hydrogen bond . That's why the boiling point of water is higher than alcohol
Question: 476
Write electronic configuration of Neon and Berylium
Answer: 476
476-861
Atomic number of Neon 10
Question: 477
Describe endothermic reaction with example .
Answer: 477
477-861
Endothermic reactions are those reactions in which heat is absorbed in theses reactions test tubes becomes cold
Question: 478
Why ionization energy of Na is less than Mg?
Answer: 478
478-861
Ionization energy of Na is less than Mg because Na requires less energy to lose its valence electron than magnesium. Ionization energy is that energy, which is required to remove outermost electrons from the gaseous state of an element.
Question: 479
Write electronic configuration of Sulphur .
Answer: 479
479-861
Electronic configuration of Sulphur :
Question: 480
Why water is called universal solvent ?
Answer: 480
480-861
Water is called universal solvent because it dissolves almost all the solute particles present in the world
Question: 481
Which factor controls the non-metallic character of the element?
Answer: 481
481-861
The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity
Question: 482
Write any four examples of colloidal solution .
Answer: 482
482-861
1: Starch
Question: 483
Differentiate between shell and sub shell and give example .
Answer: 483
483-861
Sub shell :
1: Every main energy level or shell which have sub energy level (s) or shell are called sub shell
2: They are represented by small letter s, p, and f
Question: 484
Calculate the value of angular momentum of 1st orbit where mvr = nh/2π
Answer: 484
484-861
Let angular momentum (mvr) of first orbit is =mvr = nh/2π
Question: 485
Name the metal which is the poorest conductor of heat ?
Answer: 485
485-861
Lead is the poorest conductor of heat
Question: 486
Why elements of group 1 and group 2 are called S block elements?
Answer: 486
486-861
There are four blocks in the periodic table named after the name of the subshell which is in the process of completion by electrons .
Question: 487
Which salt is used as electrolyte in chromium electroplating ?
Answer: 487
487-861
In electroplating of chromium Sulphate Cr2(SO4)3 is used an electrolyte
Question: 488
Write down atomic number of nitrogen and oxygen .
Answer: 488
488-861
The atomic no of N2 is = 7
Question: 489
Define reduction .
Answer: 489
489-861
Reduction is defined as addition of hydrogen or removal of oxygen during a chemical reaction
Question: 490
What is the trend of electronegativity in the period ?
Answer: 490
490-861
The trend ofelectronegativity is same as of ionization energy and electron affinity . It increases in a period from left to right because higher Zeff shortens distance from the nucleus of the shared pair of electrons . This enhances the shared pair of electron
Question: 491
In electroplating of silver , from which electrolyte Ag+ come or where they deposit ?
Answer: 491
491-861
In the electrolyte of silver (Ag+) comes from anode and deposit on cathode
Question: 492
How many neutrons are there in C-12 , C-13 ?
Answer: 492
492-861
1: C-12 has 06 neutrons
2: C-13 has 07 neutrons
Question: 493
Define carbondating .
Answer: 493
493-861
1: The radioactive isotopes are used to estimate the age of fossils like dead plants and animals and stones etc . The age determination of very old objects based on the half-lives of the radioactive isotopes is called radioactive isotopes is called radioactive-isotopes dating
Question: 494
Write down uses of radioactive isotopes as traces for diagnosis and medicine .
Answer: 494
494-861
1: The radioactive isotopes are used as tracer to diagnose the presence of tumor inside the body
Question: 495
Define Mendeleev's periodic law .
Answer: 495
495-861
Mendeleev arranged the known elements (63) in the order of increasing atomic masses in the horizontal rows called periods . So that elements with similar properties were in the same vertical columns . This arrangement of elements was called periodic table . According toMendeleev's periodic law properties of the element are periodic function of their atomic masses
Question: 496
Define redox reaction , Give an example .
Answer: 496
496-861
The reaction in which oxidation as well as reduction takes place at a time called redox reaction
Question: 497
Write electronic configuration of Chloride ion Cl-
Answer: 497
497-861
Electronic configuration of Chloride ion
Question: 498
Why does atomic size increases in a group ?
Answer: 498
498-861
The size of atoms or their radii increases from top to bottom in a group . It is because a new shell of electrons is added up the successive period . Which the effect of nuclear charge
Question: 499
Define freezing point ?
Answer: 499
499-861
The temperature at which liquid and solid coexist at dynamic equilibrium is called freezing point
Question: 500
How many sub shell are there in second sub shell ?
Answer: 500
500-861
In second sub shell 'L ' has two sub shells s and p
Question: 501
Which isotopes are called radioactive isotopes ?
Answer: 501
501-861
The isotopes have ability to emit radiation naturally called radioactive isotopes
Question: 502
Differentiate between ionic bond and covalent bond .
Answer: 502
502-861
Ionic Bond :
The type of chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond
Question: 503
How can you justify that milk is a colloid?
Answer: 503
503-861
Milk is a colloid . It can be justified on the basis of tyndall effect . Itsa solute particles are larger but not enough and can't seen by naked eye amd not settled down after long time and show tyndall effect , So milk is colloid
Question: 504
Define Crystalline solids and give two examples .
Answer: 504
504-861
Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids
Question: 505
What are anode or cathode ?
Answer: 505
505-861
Anode : It is the electrode at which the oxidation takes place
Question: 506
Give two examples of suspension .
Answer: 506
506-861
1: In suspension the undissolved particles are big enough to be seen with the naked eye
Question: 507
Write two physical properties of sodium hydroxide .
Answer: 507
507-861
1: NaOH is crystalline solid at room temperature
Question: 508
On which two factors vapour pressure of any liquid depends ?
Answer: 508
508-861
Vapour pressure of liquid depends upon following factors :
Question: 509
Why solution is considered mixture ?
Answer: 509
509-861
The chemical reaction did not take place between the components of solution and the components kept constant their properties . That's way solution is considered mixture .
Question: 510
State the physical properties of sodium .
Answer: 510
510-861
1: Its melting point is 97°C
Question: 511
What is meant by periodic function ?
Answer: 511
511-861
Repetition of properties due to increases of atomic number after regular intervals in the periodic table is called periodic function
Question: 512
What is the half cell reactions occuring on cathode and anode in Daniel cell ?
Answer: 512
512-861
Following reactions occur at cathode and anode in Daniel cell .
Question: 513
Why ionization energy of Na is less than Mg ?

Answer: 513
513-861
Ionization energy of Na is less than Mg because Mg has greater nuclear charge than Na and also have smaller size
Question: 514
Define polar covalent bond with example .
Answer: 514
514-861
Polar covalent bond is formed between two different atoms when the shared pair of electrons are not attracted equally by bonded atoms. The compounds resulting from covalent bond are called polar compounds
Question: 515
What is difference between solute and solvent ?
Answer: 515
515-861
Solute : The component of the solution which is present in smaller quantity is called solute
Question: 516
What type of solution fog and brass are?
Answer: 516
516-861
1: Fog is a solution of liquid solute in gas solvent
Question: 517
Define allotropy and give examples .
Answer: 517
517-861
The existence of an element in more than one form in same physical state but different chemical properties is called allotropy .
Question: 518
What happens to iron in the rusting process ?
Answer: 518
518-861
The oxidation of iron take place during rusting process and forms Fe2O3 . The chemical formula of rust is Fe2O3nH2O
Question: 519
Write two uses of isotopes
Answer: 519
519-861
1: In the field of medicine isotopes of iodine 131 are use for diagnose of goiter in thyroid gland
Question: 520
Differentiate between crystalline and amorphous solid .
Answer: 520
520-861
Crystalline solid : Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solid
Question: 521
Name the element of 1st period of periodic table
Answer: 521
521-861
1st period consists only two elements hydrogen (H2|) and Helium ( He)
Question: 522
What ammendment was made by H.Moseley in mendeleev periodic table ?
Answer: 522
522-861
According to mendleeve's periodic table properties of the element are periodic function of their atomic mass . Whereas according to H . Moseley's ammendments of periodic law properties of the elements are periodic function of their atomic numbers . This shows an atomic number of an element is equal to the number of electrons in a neutral atom . So atomic number provides the basis of electronic configuration as well .
Question: 523
What is the nature of electrode used in electroplating chromium ?
Answer: 523
523-861
During electroplating chromium the object to be electroplated act as cathode with anode is made up of antiamonial lead
Question: 524
What is difference between Duplet rule and octet rule ?
Answer: 524
524-861
Duplet rule : Attaining two electrons in the valence shell is called duplet rule
Question: 525
Define solubility ?
Answer: 525
525-861
The amount of solute in grams dissolved in 100g of solvent to prepare saturated solution at a particular temperature is called solubility of solute .
Question: 526
Ice floats on the surface of water . Give reason.
Answer: 526
526-861
Floating of ice over water is because of hydrogen bonding . The density of ice at0°C (0.917gcm-3) is less that of liquid water at0°C(1.00 gcm-3) In the liquid state water molecules move randomly . However , when water freezes , the molecules arrange themselves in an ordered form , that gives them an open structure . This process expands the molecules , that results in ice being less dense as compared to water
Question: 527
What is the colour of flame when sodium and calcium burn in air ?
Answer: 527
527-861
1: Sodium burns in air and produce golden yellow flame
Question: 528
Why solid show rapidly ?
Answer: 528
528-861
The particles of solids are fixed at their position and are not mobile . Therefore they have rigid structure and definite shape .
Question: 529
Write down names of any two moderate reactive metals
Answer: 529
529-861
1: Magnesium
Question: 530
Define Shielding effect.
Answer: 530
530-861
The force of attraction between the nucleus and valence electrons is reduced due to the presence of internal - sell electrons , This effect is called shielding effect
Question: 531
If we add 5cm3 of acetone in water to prepare to prepare 90cm3 of aqueous solution .Calculate the concentration (%v/v) of this solution .
Answer: 531
531-861
Using the relationship :
Question: 532
Write down four important chemical properties of metals .
Answer: 532
532-861
1: Metals easily lose electron and form positive ions
Na➜ Na +1 +le-
Question: 533
Name the elements of first group .
Answer: 533
533-861
1: Hydrogen (H)
Question: 534
Write difference between saturated solution and unsaturated solution .
Answer: 534
534-861
Saturated solution : The solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 535
Why is 2nd ionization energy of magnesium very high than its 1st ionization energy
Answer: 535
535-861
Second ionization energy of magnesium is very high than its first ionization energy . Because it becomes very difficult to remove second electron from the Mg- ions as the nuclear charge attracts the remaining electrons strongly
Question: 536
Why calcium is more electropositive than to magnesium?
Answer: 536
536-861
Calcium is more Electropositivity than magnesium because metallic character or electroposltve character or electropositive character down the group increases due to loosely held and can be easily with drawn from their shells.
Question: 537
What are metalloids ? Give two examples .
Answer: 537
537-861
The elements whose properties are intermediate between metals and non-metals are called metalloids
Question: 538
What is difference between solution aqueous solution ?
Answer: 538
538-861
Solution : A solution is a homogenous mixture of two or more substance
Question: 539
Differentiate between Lone pair and bond pair of electrons .
Answer: 539
539-861
Long pair : The pair of electrons which remain unshared during covalent bond formation is called long pair
Question: 540
Give two characteristics of colloid .
Answer: 540
540-861
1: Colloid particles are large but can't be seen with naked eyes
Question: 541
How platinum is used as a catalyst in automobiles and what are advantages of this use ?
Answer: 541
541-861
Platinum alloyed with palladium and rhodium is used as a catalyst in automobile as catalyst converter . It converts harmful gases into harmless gases
Question: 542
What is electronegativity ? Write its unit .
Answer: 542
542-861
The ability of an atom to attract the shared pair of electrons towards itself in a molecule is called electronegativity
Question: 543
Write down names of two very reactive metals .
Answer: 543
543-861
1: Li (Lithium)
Question: 544
Define aqueous solution . Write its components .
Answer: 544
544-861
The solution which is formed by dissolving substance in water is called an aqueous solution . Water in the solution always in large amount and are called solvents
Question: 545
Define molarity and write its equation .
Answer: 545
545-861
It is a concentration unit defined as number of moles of solute dissolved in one dm3 of solution . It is represented by M.
Question: 546
What are trends of ionization energy in periodic table ?
Answer: 546
546-861
Ionization energy increases from left to right in the period while it decreases from to bottom in a group
Question: 547
Why covalent bond in H2 is non-polar ?
Answer: 547
547-861
In H2 covalent bond is formed between two similar atoms , the shared pair of electron is attracted by both atoms equally , so non-polar covalent bond exist between hydrogen atoms
Question: 548
Why is the ionization energy of Na more than 'K'?
Answer: 548
548-861
The first ionization of Na (495,8kJ/mol ) is greater than first ioniztaion energy of 'K' (418.8kJ(mol) and the atomic size of Na is less than 'K' so the energy required to remove an electron from outermost shell of Na is greater than that ok K ,so the ionization energy of Na is more than k
Question: 549
Name the best ductile and malleable metal ?
Answer: 549
549-861
Gold and silver
Question: 550
Why the second ionization energy of magnesium is higher than than first ?
Answer: 550
550-861
Second ionization energy of magnesium is higher than than first , because it is very difficult to remove the second electron from the Mg+ ion due to much nuclear attraction . As a result of this attraction , size of ions decreases . Due to this reason , the second ionization energy of magnesium is higher than the first
Question: 551
Why is calcium more electropositive than magnesium ?
Answer: 551
551-861
Calcium is more electropositive than magnesium due to its large atomic size and less amount of ionization energy
Question: 552
Why is naphthalene soluble in carbon tetrachloride and not in water ?
Answer: 552
552-861
Non -polar covalent substances are soluble in non-polar solvents due to this reason , naphthalene is soluble in carbon tetrachloride and not soluble in water because water is a polar solvent
Question: 553
Define Newland octaves law ?
Answer: 553
553-861
In 1864 British chemist Newlands put forward his observations in the form of law of octaves . He noted that there was a repetition in chemical properties of every eight element if they are arranged by their increasing atomic masses
Question: 554
Write two examples of gas into gas solution .
Answer: 554
554-861
1:Air
Question: 555
What is electropositivity ? Explain with example
Answer: 555
555-861
Electropositivity : Metals have the tendency to loose their valence electron from their valence shell . The property of the metal is termed as electropositivity or metallic character
Question: 556
Give two examples of gas in liquid solution .
Answer: 556
556-861
1: Fog
Question: 557
Can pure gold be used for making ornaments?If not why?
Answer: 557
557-861
No. pure gold cannot be used for making ornaments.
because gold is too sift to be used as such It is always alloyed with copper. silver and some other metals

Question: 558
Explain the effect of temperature on solubility .
Answer: 558
558-861
1: Temperature has major affect on the solubility of most of the substances
Question: 559
Define oxidation and reduction reaction .
Answer: 559
559-861
Oxidation: Oxidation is defined as addition of oxygen or removal of hydrogen or electron during a chemical reaction
Question: 560
What is meant by ' Like dissolves like'
Answer: 560
560-861
1: The general principle of solubility is like dissolve like . The polar substance are soluble substances are soluble in polar solvents . Ionic solids and polar covalent compounds are soluble in water
Question: 561
Two hydrogen atoms combine to form molecules H2 while 'He' atom remains monatomic . Explain ?
Answer: 561
561-861
Two hydrogen atoms combine to form molecules H2 while 'He' atom remains monatomic because the outer most shell of hydrogen is incomplete . On the other hand outer most shell of He is complete
Question: 562
What is difference between steel and stainless steel ?
Answer: 562
562-861
Steel : Alloy of iron with other metals called steel
Question: 563
Magnesium has electronic configuration 2,8,2 .Why magnesium tend to lose electron ?
Answer: 563
563-861
electronic configuration of magnesium is 2,8,2 . There are 2 electrons in its valence shell . It lose 2 electrons and get stable electronic configuration like noble gas Ne
Question: 564
How will you test weather given solution is colloidal solution or not ?
Answer: 564
564-861
Colloidal solution show tyndall effect and other solutions do not show tyndall effect
Question: 565
Can pure gold be used for making ornaments ? If not , why ?
Answer: 565
565-861
Gold is too soft ,to be used as such . That is why it cannot be used aline in making ornaments . It is always alloyed with copper ,silver or some other metals
Question: 566
Why silver is not used in pure form ?
Answer: 566
566-861
Silver is a very soft metal that's why it is not used as such in pure
Question: 567
Write down two uses of gold .
Answer: 567
567-861
Because of its inertness in atmosphere , it is an ornamental metal as well as used in making coins . Gold is too soft to be used as such
It is always alloyed with copper, silver or some other metal
Question: 568
For what purpose is U-235 used ?
Answer: 568
568-861
The radioactive isotopes are used to generate electricity by carrying out controlled nuclear fission reaction in nuclear reactions e.g U-235 is bombarded with slow moving neutrons . The uranium breaks to produce Barium - 139 and Krypton - 94 and three neutrons . A large amount of energy is released which is used to convert water into steam boilers . The steam drives the turbine to generate electricity . This is the peaceful use of atomic energy
Question: 569
How can you justify that blood is a colloid?

Answer: 569
569-861
Blood appears to be a homogenous but actually it is a heterogeneous mixture. Blood particles do not settle down for a long time so we can say that blood is a colloidal solution
n
Question: 570
Define oxidizing and reducing agents with example .
Answer: 570
570-861
Oxidizing agent:
1: Oxidizing agent is the species that oxides a substance by taking electrons from it
2: The substance (atom or ion ) which is reduced itself by gaining electrons is also called oxidizing agent

Question: 571
Define single covalent bond and give one example .
Answer: 571
571-861
'When one electron is contributed by each bonded atom ,one bond pair is formed and it forms a single covalent bond '
Question: 572
What is general principle of solubility ?
Answer: 572
572-861
The general principle of solubility is ' like dissolve like ' . The polar substance dissolve in polar substance and non-polar substances and non-polar substances dissolve in non-polar substance
Question: 573
How many groups and period and periods are there in modern periodic table
Answer: 573
573-861
1: Long form of periodic table consists of seven horizontal rows called periods
Question: 574
Identify as colloids and suspensions : paints, jelly, soap solution , milk , milk of magnesia , chalk in water .
Answer: 574
574-861
Colloid : Soap solution , Milk , Jelly
Suspension : paints , milk of magnesia , chalk in water
Question: 575
Define non polar covalent bond and give example .
Answer: 575
575-861
Non polar covalent bond is formed between two similar atoms the hsred pair of electrons is attracted by both the atom equally
Question: 576
How can we distinguish a metal from non-metal by a simple physical method ?
Answer: 576
576-861
Metals : On heating metals usually become soft and flexible
They are difficult to cut
Question: 577
What is difference between colloidal and suspension ?
Answer: 577
577-861
Colloid : The particles of colloid are large consisting of many atoms , ions or molecules . Particles are large but can't be seen with naked eye
Question: 578
Why do suspensions not form the homogeneous mixture ?
Answer: 578
578-861
The force of attraction does not develop between particles of solvent and solute in the suspensions , due to this , suspension does not from homogeneous mixture
Question: 579
What are electrolytic cell ?
Answer: 579
579-861
Electrolytic cell : The type of electrochemical cell in which the non-spontaneous chemical reaction is carried out with the help of electric current is called electrolytic cell
Question: 580
What is the electronegativity of hydrogen and chlorine ?
Answer: 580
580-861
1: Value of electronegativity of hydrogen (H) is 22
Question: 581
Which factors affect the non-metallic character ?
Answer: 581
581-861
Non-metallic character depends upon Electron affinity and electronegativity

Question: 582
Write ant two chemical properties of non-metals .
Answer: 582
582-861
1 : Non-metals usually do not react with water
2: They do not react with dilute acids because non-metals are itself electron acceptors

Question: 583
Write down two significance of non-metals
Answer: 583
583-861
1: Non-metals are essential part of the body structure of all living things . Human body is made up of about 28 elements . But about 96% of the mass
of the human body is made up of just 4 elements i-e oxygen 65% carbon 18%, hydrogen 10% , and nitrogen 3% . Similarly plant bodies are made up of cellulose,
which is compose of carbon , hydrogen , and oxygen
Question: 584
Write the symbol of noble gasses
Answer: 584
584-861
1: Helium (He)
Question: 585
What is pacemaker ?
Answer: 585
585-861
A pacemaker is a small device in which body fluids act as an electrolyte . This device uses electrical pulses to prompt the heart to beat at a normal rate
Question: 586
Give difference between solution and colloids .
Answer: 586
586-861
Colloids :
The particles of colloids are large consisting of many atoms , ions , or molecules
Question: 587
Define hydrogen bonding ?
Answer: 587
587-861
Th partially positive charged hydrogen atom of one molecule attracts and forms a bond with partially negatively charged atom of the other molecule the bonding is called hydrogen bonding
Question: 588
Write any two properties of solution and suspension
Answer: 588
588-861
Solution :
1: A solution is a homogeneous mixture of two or more substances
Question: 589
Write down the position of hydrogen in the periodic table
Answer: 589
589-861
First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 590
Define biotechnology?
Answer: 590
590-861
It deals practical of living organism to make substances for the welfare of mankind

Question: 591
Write down the position of hydrogen in the periodic table
Answer: 591
591-861
First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 592
Why O2 is necessary for rusting ?
Answer: 592
592-861
Rusting is the oxidation of any metal . The important condition for rusting is moist air (air having water vapours formed which is called rust . In the absence of oxygen this reaction did not take place due to which rusting dis not happen
Question: 593
Why nitrogen is necessary for safety of life on earth ?
Answer: 593
593-861
Nitrigen is 78% in atmosphere and is necessary for safety of life on earth . It controls the fire and combustion process ,
otherwise all the things around us could burn with a single flame

Question: 594
Give chemical reaction of methane with chlorine in bright light .

Answer: 594
594-861
In bright light (sun light) Cl2 react with CH4 violently and explosively
Chemical reaction : CH4 +2Cl2 ➜ C+4HCL
Question: 595
Calculate the oxidation number of chlorine in KClO3 .
Answer: 595
595-861
{O.N of K } + {O.N of Cl } +3 {O.N of O } =0
{ +1 } + {O.N of Cl } +3 {-3} = 0
{O.N of Cl} + {1} +{-6} =0
{O.N of Cl } +1-6 =0
O.N of Cl {-5} =0
O.N OF Cl =5
Question: 596
How electro positivity depends upon size and nuclear charge of an atom?
Answer: 596
596-861
Electropositivity depends upon size and nuclear charge of an atom because when the size of atoms increases. Electropositivity increases as it becomes easier to lose electrons. It also depends upon nuclear charge if nuclear energy increase the electropositivity decreases because it becomes difficult to remove the electrons from outermost shell
Question: 597
In electroplating of silver , from which electrolyte Ag+ comes and where they deposit ?
Answer: 597
597-861
In the electrolyte of silver (Ag)+ comes from anode and deposit on cathode .
Question: 598
Why we stir paints thoroughlybefore use ?
Answer: 598
598-861
Paint is a suspension and there are undissolved particles in the suspension which are seen with naked eye . These particles settled down after some time .That's why we stir paints thoroughly before use
Question: 599
How chlorine chemical react with dilute ?

Answer: 599
599-861
Chlorine react withcold dilute NaCl to give sodium hypochlorite
2NaOH +Cl2 ➜ NaCl +NaOCL + H2O

Question: 600
Define ionization energy .
Answer: 600
600-861
Ionization energy is the minimum amount of energy required to remove the most loosely bound electron from the valence shell of an isolated gaseous atom
Question: 601
Write four physical properties of metals
Answer: 601
601-861
1: Almost all metals are solid (Except mercury)
Question: 602
Why magnesium is harder than sodium?
Answer: 602
602-861
Magnesium is harder than sodium because in magnesium metallic bonding is stronger. While sodium is relatively soft metal due to weak metallic bonding in their atoms.
Question: 603
What are non - electrolytes .Give one example
Answer: 603
603-861
The substances , which do not ionize in their aqueous solutions and do not allow the current to pass through their solutions are called non-electrolytes
Question: 604
What is difference between Mendeleev's periodic law and modern periodic law?

Answer: 604
604-861
Mendeleev's periodic law : The properties of elements are the periodic function of atomic masses
Question: 605
How can you differentiate between organic and inorganic chemistry .
Answer: 605
605-861
Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
Question: 606
Write down the name of four least reactive metals .
Answer: 606
606-861
The names of least reactive metals are following
Question: 607
Why sodium metal is more reactive than magnesium metal?
Answer: 607
607-861
Sodium metal is more reactive than magnesium metal because electro-positivity of met increase along the periods from left to right in periodic table. Element in the start of the period are more metallic or electropositive. Across the period from left to right size of atoms decreases due to increase in nuclear charge. That's why, sodium is more reactive than magnesium.
Question: 608
What happens at cathode in galvanic cell ?
Answer: 608
608-861
Reduction process takes place at cathode in galvanic cell
Cu+2 + 2e➜ Cu
Question: 609
How does homogenous mixture differ from heterogenous mixture ?
Answer: 609
609-861
Homogenous mixture : Mixtures that have uniform composition through are called homogenous mixture
Question: 610
Give the scope of biochemistry .
Answer: 610
610-861
It is the branch of chemistry in which we study the structure , composition and chemical reaction of substances found in living organisms . It covers all chemical processes taking place in living organisms . Such as synthesis and metabolism of bio molecules like carbohydrates , proteins and fat . Biochemistry emerged as separate discipline when scientists began to study how living things obtain energy from food or how the fundamental biological changes occur during a disease . Examples of applications of biochemistry are in the fields of medicine , food science and agriculture etc
Question: 611
Write names of any two noble metals
Answer: 611
611-861
1: Copper
Question: 612
How many normal periods are and name also?
Answer: 612
612-861
2nd and 3rd periods are known as normal periods and they are two in number
Question: 613
What is the shape of cathode in the Nelson's cell ? Why is it perforated ?
Answer: 613
613-861
The cathode in Nelson's cell is U- shaped . It is perforated for the percolation of NaoH into a catch basin
Question: 614
Why HF is a weak acid ?
Answer: 614
614-861
HF is a weak acid because in HF -compound . There is strong intermolecular bonding . So, it does not readily ionize in water and release H+ in water the strong acid is that which is readily ionized in water but HF does not easily ionized in water
Question: 615
Describes the trends of electropositivity in a period and in a group .
Answer: 615
615-861
Electropositive character increase down the group because size of atoms increase and nuclear charge decrease . Electropositive character decreases across the period from left to right because atomic size decrease and nuclear charge increase
Question: 616
What is galvanizing ?
Answer: 616
616-861
1: The process of coating a thin layer of zinc on iron is called galvanizing
Question: 617
How are elements are arranged in 4th period ?
Answer: 617
617-861
In fourth period 18 elements are arranged in the ascending order of their atomic number
Question: 618
Why oxygen is called non-metal?
Answer: 618
618-861
Non-metals form negative ions by gaining electrons. Oxygen atoms can accept 2 electrons therefore its valency is 2. 0+2e-0-2
Question: 619
Difference between substance and mixture.
Answer: 619
619-861
Substance: A piece of matter in pure form is termed as substance.
e.g. Glucose (C6H12O6) Oxygen
Question: 620
Why silver and gold are least reactive ?
Answer: 620
620-861
From the transition metals of group 11 of periodic table Silover and Gold are least reactive because they do not lose electron easily

Question: 621
What is periodic law?
Answer: 621
621-861
In 1913, H. Moseley observed that atomic number instead of atomic mass should determine the position of elements in the periodic table and according the periodic law was amended as properties of elements are periodic function of their atomic numbers
Question: 622
What do you mean by malleable and ductile ?
Answer: 622
622-861
Malleability is the property by virtue of which metals can be drawn into sheets while ductility is the properties by virtue of which a metal can be drawn into wires
Question: 623
Why noble gases are not reactive ?
Answer: 623
623-861
The noble gases have 2 or 8 electrons in their valence shells i-e the valence shell of all the noble gases is complete . Their atoms do not have vacant space to accommodate extra electrons , So noble gases are not reactive
Question: 624
Write two physical properties of magnesium .
Answer: 624
624-861
Magnesium is good conductor of heat and electricity
Question: 625
Differentiate between molecular mass and formula mas , which of the following is molecular formula ?
. H2O
.NaCl
.Kl
.H2SO4
Answer: 625
625-861
Molecular mass :
The sum of atomic masses of all the atoms present in one molecule of a molecular compound is its molecular mass

Question: 626
Which one has more molecules : 9 g of water or 9 g of sugar C12 H22 O11 ?
Answer: 626
626-861
9g of water has more molecules than 9 g of sugar because moles of water are more than sugar
For water
Question: 627
Which has more atoms :10g of Al or 10 g of Fe ?
Answer: 627
627-861
10 g of A 1 has more atoms than 10 g of Fe
For A 1

Question: 628
Write two physical properties of non-metals.
Answer: 628
628-861
1: Non-metals have less melting and boiling point (except diamond)
2: They are generally soft (except diamond)

Question: 629
What are spontaneous and non- spontaneous reaction ? Differentiate them
Answer: 629
629-861
Spontaneous reaction : The reaction which proceed without any external assistance and heat are called spontaneous reaction .These reactions takes place in galvanic cells
Question: 630
Why is gold used to make jewelry?
Answer: 630
630-861
Gold is very nonreactive or inert metal. It is not affected by atmosphere. It is not affected by any single mineral acid or base. It is most malleable and ductile of all the metals. Due these reasons the gold is used to make jewelry.
Question: 631
Why the elements of group 13 to group 18 are called P block elements ?
Answer: 631
631-861
Elements of group 13 to 18 have their valence electrons in P subshell . Therefore , they are called as P-block elements
Question: 632
Define reduction on the basis of electron and give example .
Answer: 632
632-861
Reduction reaction : The gain of electrons by atom or ion is called reduction reaction .
Question: 633
Which is most precious metal ?
Answer: 633
633-861
The most precious metal is platinum
Question: 634
Determine the oxidation number of Mn in KMnO4.
Answer: 634
634-861
{O.N k } + {O.N Mn } +4 {O.N O} =0
{+1} + {O.N Mn } +4 {-2 } =0
1+ {O.N Mn } 8=0
O.N Mn = 8-1
= 7
Question: 635
Give chemical reaction between Methane (CH4) and chlorine (Cl2) in presence of diffused light .
Answer: 635
635-861
CH4 + Cl2 ➜ CH3Cl +HCL
CH3Cl +Cl2 ➜ CH2Cl2+HCL
CH2Cl2 + Cl2 ➜ CHCl2 +HCL
CHCL3 + Cl2 ➜ CCl4 ➜ CCl4 +HCL
Question: 636
Write down the trend of atomic size in the periodic table.
Answer: 636
636-861
In period : Atomic size in a period from left to right decreases
Question: 637
Define electrolyte . Give an example .
Answer: 637
637-861
Electrolyte : The substance which can conduct electricity in their solution or molten states are called electrolytes . Salts and acids are good electrolytes
Question: 638
Define metallic character .
Answer: 638
638-861
The property of a metal to loose its valence electrons to form a positive ion is called metallic character
Question: 639
Why size of an atom decreases from left to right in the periodic table?
Answer: 639
639-861
When we move from left to right in a periodic atomic number increase yet the size of atoms decrease gradually . It is because with the increase of atomic number and nuclear charge
Question: 640
What are electrolytes or non-electrolytes ?
Answer: 640
640-861
Electrolytes : The electrolytes which can conduct electricity in their aqueous solution of fuse form and produce more ions are called electrolytes
Question: 641
Define industrial chemistry and analytical chemistry
Answer: 641
641-861
Industrial chemistry : This branch of chemistry is related to the industrial process . It is associated with studies of properties uses and application of techniques for the preparation of industrial sales on large scale
Question: 642
Which are long periods ? How many elements are present in long periods ?
Answer: 642
642-861
4th and 5th periods of the long firm of table are called long periods of periodic table . Both these periods consists on 18 elemensts present in each
Question: 643
Is triple covalent bond stronger than double covalent bond ? Give reason
Answer: 643
643-861
In triple covalent bond , three shared electron pair is involved while double covalent bond is formed between two shared electron pair . The greater number of shared pair electron , the bond will be stronger . That's why triple covalent bond is stronger than double covalent bond
Question: 644
What is salt bridge ? What is its basic function ?
Answer: 644
644-861
Galvanic cell consists of two half cells, both these half cells are connected by salt bridge
Question: 645
Why do ionic compound conduct electricity in solution form . Give reason
Answer: 645
645-861
Ionic compounds are found in the form of positive and negative ions when they are in solution or molten form . When these programs are connected through a battery their ions create an opportunity for an electron (charges) to move rapidly and current begins to flow Therefore , this flow of current proved that ionic compounds are good conductors and they conduct electricity in solutions or molten form
Question: 646
State the nature and name of the substance formed by combining the following
1: Zinc + Copper
2: Water +Sugar
3: Aluminum +Sulphur
4: Iron + Chromium + Nickle
Answer: 646
646-861
1:Zinc + Copper
It will be a mixture called a brass (alloy)
Question: 647
What do you means by 24 carat gold ?
Answer: 647
647-861
1: Purity of gold is show by carats .

Question: 648
What is difference between corrosion and rusting ?
Answer: 648
648-861
Corrosion : Corrosion is slow and continuous eating away a metal by the surrounding medium . It is a redox reaction which takes place on metals by the action of air and vapours
Question: 649
Give uses of platinum
Answer: 649
649-861
Uses of platinum :
1: Platinum is used in hard disk coating and in maufacturing fibre optic cables

Question: 650
Give the composition of milk .
Answer: 650
650-861
Milk is a mixture of calcium , water ,sugar , fat , proteins , minerals, salts , and vitamins
Question: 651
Differentiate between homogenous and heterogenous mixture .
Answer: 651
651-861
Homogenous Mixture : Mixtures that have have uniform composition throughout are calledhomogenous mixture
Question: 652
Which six elements constitute 99% of body mass and what are their percentages ?
Answer: 652
652-861
Following six elements constitute 99%of body mass
Oxygen 65%
Hydrogen 10%
Calcium 1.5 %
Carbon 18%
Nitrogen 3%
Phosphorous 1.5%
Question: 653
In the basis of properties , elements are divided into which group ?
Answer: 653
653-861
On the basis of properties elements are divided into metals , non-metals and metalloids
Question: 654
Define brine ?
Answer: 654
654-861
The by-product in Nelson's cell are hydrogen gas (H2) and chlorine gas (Cl2)
Question: 655
Why does oxygen molecule not form a polar covalent bond ?
Answer: 655
655-861
In oxygen molecule formed by hydrogen and oxygen and hence there will be electronegativity difference between the oxygen and hydrogen . Due to which oxygen atlain negative and hydrogen atlain positive charge
Question: 656
What is meant by atomic radius ? What is its unit ?
Answer: 656
656-861
The half of the distance between the nuclei of two of similar adjacent (bonded) atoms is called atomic radius
Question: 657
Why ionization energy decreases in a group from top to bottom ?
Answer: 657
657-861
When we move down the group in periodic table , more and more shells lie between the valence shell and nucleus of the atom , these additional shells reduce the electrostatic force felt by electrons present in the outermost shell . Resultantly the valence shell electrons can be taken away easily . Therefore , ionization energy of elements decreases from top to bottom in the groups
Question: 658
Why fluorine is more non-metallic than chlorine ?
Answer: 658
658-861
Fluorine is more reactive than chlorine because the electronegativity of fluorine is greater tahn chlorine

Question: 659
Why electro positivity decreases from left to right in a period?
Answer: 659
659-861
Electropositivity decreases across the period from left to right. It means elements in the start of periodic are more metallic. This is because of two reasons,
(i) Size of atoms decreases.
(ii) Nuclear charges increases. upon nuclear charge. If nuclear charge increases the Electropositivity decreases because it becomes difficult to remove the electrons from outermost shell
Question: 660
What is meant by electroplating ?
Answer: 660
660-861
Electroplating is depositing of one metal over the other by means of electrolysis
Question: 661
Define alloy and give example .
Answer: 661
661-861
Alloy : alloy is a homogeneous mixture of one metal with one or more metals or non-metals
Question: 662
hat is the importance of oxygen and carbon dioxide for plants and animals ?
Answer: 662
662-861
Life owes to non-metals as without O2 and CO2 those are essential gases for respiration of animals and plants respectively , life would not have been possible . In fact these
gases are essential for the existance of life
Question: 663
What is an electron affinity ? Give an example .
Answer: 663
663-861
Trend in a group : In a group electron affinity values decreases from top to bottom because the size of an atom increases down the group . With the increase in size of atom shielding effect increase that results in poor attraction for the incoming electron i-e less energy is released out
Question: 664
What is the nature of metal oxide?
Answer: 664
664-861
When metals react with oxygen they form metallic oxide, which are basic in nature. 2Mg+022Mg0
Question: 665
Can liquid and gases be brittle?
Answer: 665
665-861
No, Only solid non-metals are brittle.
Question: 666
State three reasons why do you thing soft drink is a mixture and water is a compound .
Answer: 666
666-861
Soft drink is a mixture because :
1: Its components are not bounded chemically
2: The components do not have fix ratio
Question: 667
Define metal and give two examples .
Answer: 667
667-861
The elements which have ability to lose electron and forms cations called metals like Na , K , Ca
Question: 668
Write down names of elements of first group and second period of the periodic table .
Answer: 668
668-861
First group of periodic table consists of hydrogen , lithium , sodium , potassium , rubidium , cesium , francium
Question: 669
Complete the following chemical equation .
Answer: 669
669-861
NaO +H2O➜ 2NaOH
Question: 670
Write the redox reaction taking place during the electroplating of chromium .
Answer: 670
670-861
Chromium sulphate Cr(SO4)3 used as an electrolyte in the electroplating of chromium that provides CCr+3 ions which reduce and deposit at cathode
Question: 671
What are applications of inorganic chemistry?
Answer: 671
671-861
It has application in every aspect of chemical industry such as glass , cement , ceramics and metallurgy
Question: 672
Why is platinum is used to make jewelry ?
Answer: 672
672-861
Platinum is used to make jewelry items because of its unique characteristics like colour , beauty , strength, flexibility and resistance to tarnish . It provides a secure setting for diamonds and other gemstone , enhancing their brilliance
Question: 673
What is the sign of stability of an atom ?
Answer: 673
673-861
The sign of stability of an atom IS achieving the electronic configuration similar to noble gases (He , Ne , or Ar etc) i-e (n2 p6 ) or having two or eight electrons in their valence shell . In other words an atom is called stable if it follows duplet or octet rule
Question: 674
What is meant by variable valency ?
Answer: 674
674-861
Some elements show more than one combining power (valency) that is called variable valency
Question: 675
What is radical ?
Answer: 675
675-861
An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e,g Hydronium H3O+ and CO3 -2
Question: 676
What is valency ?
Answer: 676
676-861
The combining capacity of an element with other element is called valency
Question: 677
What is the significance of chemical formula ?
Answer: 677
677-861
1: It represents the name of the substance e.g H2O (water)
Question: 678
Is atomic mass unit a SI unit of an atomic mass ?
Answer: 678
678-861
Yes ,atomic mass unit is SI unit of atomic mass
Question: 679
What is meant by malleable and ductile metals ?
Answer: 679
679-861
Malleable : The substance that can be drawn into sheets are called malleable
Question: 680
Define oxidation in terms of oxygen with an example .
Answer: 680
680-861
Oxidation : The addition of oxygen in any chemical reaction is called oxidation reaction
Question: 681
Why the 2nd ionization energy is greater than 1st ionization energy ?
Answer: 681
681-861
Because after the removal of the first electron from the atom , its number of protons , become greater than electrons . The force of attraction between the nucleus and remaining valence shell electron increases . So more energy is required to remove the 2nd electron from the atom
Question: 682
Define chemical bond and write names of its type .
Answer: 682
682-861
A chemical bond is defined as as a force of attraction between atoms that holds them together in a molecules . In other words , during bond formation there is some force which holds the atomic together
Question: 683
Why is ionization energy of sodium is less than magnesium ?
Answer: 683
683-861
Ionization energy of sodium is less than that of magnesium ,because it becomes very difficult to remove second electron from Mg+ ions as nuclear charge attracts the remaining electrons more strongly . In the result of this attraction size of the ion decreases, So all the elements of alkaline earth metals have high ionization energies as compared to alkali metals
Question: 684
Define electrolytes and electro chemical cell .
Answer: 684
684-861
Electrolytes : The substances , which can conduct electricity in their aqueous solution or molten state , are called electrolytes
Question: 685
What is the trend of ionization energy in the group ?
Answer: 685
685-861
As we move down the group , more and more shells lie between the valence shell and the nucleus of the atom , these additional shells reduce the electrostatic force felt by the electrons present in the outermost shell . Resultantly the valence shell electrons can be taken away easily . Therefore , ionization energy of elements decreases from top to bottom in a group
Question: 686
Which force drives the non-spontaneous reaction to take place ?
Answer: 686
686-861
Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
Question: 687
Write down the reaction of magnesium with oxygen . How oxygen reacts with magnesium ?
Answer: 687
687-861
Magnesium reacts with oxygen and magnesium oxide is formed
Question: 688
What is the reason of deficiency of electrons in BF3?
Answer: 688
688-861
In the formation ofBF3molecules , three valence electrons of boron (B) make three pairs of mutual coordination with three valance electrons from three fluorine atoms .. Despite of covalent bond made due to this mutual coordination , there is still deficiency of electron in boron . That's why octate is still incomplete (BF3)
Question: 689
What is the relationship between mass and mole of a substance ?
Answer: 689
689-861
the relationship between mass and mole of a substance is given as following
Question: 690
How many molecules of water are present in half mole of water ?
Answer: 690
690-861
Water molecules in half moles = 1/2x6.02x1023
= 3.01x1023 molecules
Question: 691
How many atoms are present in one gram atomic mass of a substance ?
Answer: 691
691-861
One gram atomic mass of a substance is equal to Avogadro's number in which 6.023x1023atoms are present
Question: 692
How sodium metal is obtained from fused sodium chloride .
Answer: 692
692-861
On the industrial scale molten sodium metal is obtained by the electrolysis of fused NaCl in the Down's cell . This electrolytic cell is a circular furnace . In the center of the furnace there is a large block of graphite , which acts as an anode while cathode around it is made of iron
Question: 693
Find out the mass of 3 moles of oxygen atoms .
Answer: 693
693-861
3x16 = 48g of oxygen are present in 3 moles
Question: 694
Why atomic mass of an atom is defined as relative atomic mass ?
Answer: 694
694-861
Atomic mass of an atom is defined as a relative atomic mass , because atomic mass of an atom is the mass which compares or relates with 1/12th mass of carbon 12 isotope
Question: 695
How electropositivity depends upon the nuclear charge of an atom ?
Answer: 695
695-861
Left to right in a period nuclear charge increase but the number of metals remains same thats whyleft to right there is continuous decrease in the size of atoms . Small size atoms have higher nuclear charge and thus have lower electropositivity . Large size atoms have lower nuclear charge so they have high electropositivity , so ability to liise electron is greater large sized atoms. In high nuclear charge it is difficult to lose electron . The electropositivity of elements depends upon the nuclear charge it is difficult to lose electron . The electropositivity of elements depends upon the nuclear charge
Question: 696
What is meant by metallic bond ?
Answer: 696
696-861
When positively charged metal ions are held together by freely moving electrons , the bond which is formed called metallic bond
Question: 697
What is meant by octet rule ?
Answer: 697
697-861
Attaining 8 electrons in the outermost shell either by sharing by losing or gaining electrons is called octet rule . Atoms complete their octet by gaining , giving or sharing valence electrons with other atoms
Question: 698
Write two method for prevention of corrosion .
Answer: 698
698-861
Method for prevention of corrosion:
Following are some method from avoiding corrosion
Question: 699
Write two uses of calcium .
Answer: 699
699-861
1: It is used to remove sulphur from petroleum products
Question: 700
What is the trend of variation in densities of alkali metals?
Answer: 700
700-861
Densities of alkali metals increases down the group in the periodic table
Question: 701
Differentiate between donor atom and acceptor atom.
Answer: 701
701-861
Donor atom : The atom which donates the electron pair in coordinate covalent bond is called donor atom
Question: 702
How electroplating of zinc is carried out ?
Answer: 702
702-861
The target metal is cleaned in alkaline detergent type solutions , and it is treated with acid , in order to remove any rust or surface scales. Next the zinc is deposited on the metal by immersing it in a chemical bath containing electrolyte zinc sulphate . A current is applied , which results in zinc being deposited on the target metal i-e cathode
Question: 703
6: Complete the following chemical equation :
1: Ca + H2 ➜ , 2: Ca + Cl2
Answer: 703
703-861
Calcium reacts with hydrogen at high temperature of form hydrides
1: Ca +H2 ➜ CaH2
Question: 704
What is meant by dipole dipole forces of attraction ?
Answer: 704
704-861
When partial positive and partial negative charges exists at different positions in a molecule , the adjacent molecules will arrange themselves in such a way that negative end of that molecule comes near to positive end of other molecule . It results in a net forces of attraction between oppositely charged ends of two adjacent molecules . These attractive forces are called dipole - dipole forces
Question: 705
Why atoms form bond ?
Answer: 705
705-861
It is universal rule that everything in this world tend to become more stable . Atoms achieve stability by attaining electronic configuration (ns2 ,np6 ) like noble gases
Question: 706
Define the coordinate covalent bond? Explain with one example .
Answer: 706
706-861
Coordinate covalent bond or dative bonding is a type of covalent bonding in which the bond pair of electrons is donated by one bonded atom only . Coordinate covalent bond is also known as Dative covalent bond
Question: 707
How will you compare he electropositivity ok alkali metals and alkaline earth metals ?
Answer: 707
707-861
:Alkali metal
These are highly electropositive. They have highly ionization energy values ranging from 520k.Jmol 1 for Li to 376 k.Jmol 1 for CS
Alkaline earth metal :They have less ionization energy values ranging from 1787k.Jmol 1 for Be to 936 k.Jmol 1 for Ba

Question: 708
Define biochemistry ?
Answer: 708
708-861
It is the branch of chemistry in which we study the structure , composition , and chemical reaction of substances found in living organisms (i-e humans ,animals and plants )
Question: 709
Which metal is used for metal work?
Answer: 709
709-861
As the metal work. means fire work. The metals are used in fire work due to its characteristic flame colour when they ignite in air . Na"- give golden colour, "Ca" give red colour etc.
Question: 710
Write any two uses of sodium .
Answer: 710
710-861
1:Sodium potassium alloy is used as a coolant in nuclear reactor
Question: 711
Which branch of chemistry deals with preparation of paints and papers ?
Answer: 711
711-861
Industrial chemistry deals with preparation of paints and papers .
Question: 712
In which branch of chemistry are the metabolic processes of carbohydrates and proteins studied ?
Answer: 712
712-861
In biochemistry metabolic processes carbohydrates and proteins are studied
Question: 713
Write two properties of non-polar covalent compounds .
Answer: 713
713-861
1: They do not undergo charge separation
Question: 714
Describe at least two necessary conditions for the formation of covalent bond .
Answer: 714
714-861
1: A covalent bond is formed between two non-metals
Question: 715
What do you mean by 24 carat gold ?
Answer: 715
715-861
Purity of gold is shown by carat that indicates the number of parts by weight of gold that is present in 24 parts of alloy . Twenty four carat gold is pure and it means al the parts of alloy is gold
Question: 716
What do you mean by 1 atom of C and 1 gram of atom of C ?
Answer: 716
716-861
One atom of carbon has its atomic mass which is 12 amu . But when this mass of carbon atom atom is expressed in grams then it is known as gram atomic mass . As 1 gram of carbon = 12.0 g
Question: 717
Write the names of noble metals .
Answer: 717
717-861
The metals which give least reactions are called noble metals

Question: 718
Give example of two polar compounds and give their chemical formula .
Answer: 718
718-861
Following are some examples of two polar compounds :
Question: 719
Write uses of silver .
Answer: 719
719-861
1: Being very sift metal , it is rarely used as such . Alloys of silver woth copper are widely used in making coins , silver-ware and ornaments
2: Compiunds of silver are widely used in photographic films and dental preparations
3: Silver also has important applications in mirror industry

Question: 720
What is the difference between steel and stainless steel ?
Answer: 720
720-861
Steel is a mixture while stainless steel is an alloy
Question: 721
In which branch of chemistry behaviour of gases and liquid is studied ?
Answer: 721
721-861
The bahaviour of gases and liquid is studied in the branch of chemistry called physical chemistry
Question: 722
Metals are good conductors of electricity .Why ?
Answer: 722
722-861
Metals have free moving electrons called mobile electrons . Due to presence of these electrons metals are good conductors of electricity
Question: 723
Why silver and gold are least reactive?
Answer: 723
723-861
Silver and gold are least reactive because these metals do not lose their electrons easily. They do not have the tendency to make cations and due to their soft nature. They cannot be used as such.
Question: 724
State any four physical properties of metals.
Answer: 724
724-861
Physical Properties of Metals.
1: Almost all metals are solid except mercury.
2: Metals have high melting and boiling points. .
3:Metals possess metallic luster.
4: Malleable and ductile
Question: 725
An element has an atomic number 17 , how many electrons are present in K and M shells of an atom ?
Answer: 725
725-861
K=2 , L= 8 , M=7
An atom has atomic number 17, in first shell (K) contains 2 electrons , then second shell called (L) shell have 8 electron and 3rd shell (M) have 7 electrons
Question: 726
WHat do you know about the oxidizing characteristics of halogens ?
Answer: 726
726-861
Chlorine is the most poweful oxidizing agent. Oxidizing property of halogens is decreased from top to bottom . All halogens react with hydrogen gbas in the
presence of light and catalyst to make halides . Stability of their hydrogen halides are given below
HF > HCL > HBR > HI

Question: 727
Why ionization energies of alkaline earth metals are higher than alkali metals?
Answer: 727
727-861
Alkaline earth mewls have higher ionization energies than alkali metals because the electronic configuration of their valence shells is ns2. Their atoms are smaller and have more nuclear charge. That is why. they are reactive but less alkali metals
Question: 728
Describe the non-metallic character in groups and period of a periodic table
Answer: 728
728-861
Non-metallic charactyer in groups : In groups electrnegativity decreases from up to top bottom therefore non-metallic characrter alse decreases from top to bottom
Non-metallic charactyer in periods : In periods , electron affinity from left to right , due to which metallic character also increases
Due to this reason , fliorine is most non-metallic element in nature
Question: 729
Differentiate shell and sub-shell with example of each ?
Answer: 729
729-861
Shell (Orbit):
The circular orbits of specific energy are called shells or energy levels

Question: 730
How oxygen react with group-2 metals?
Answer: 730
730-861
They are less reactive towards oxygen and oxides are formed on heating
Question: 731
Write down melting point and boiling point of sodium metal .
Answer: 731
731-861
Melting and boiling point of sodium metal are as follows
Question: 732
Write down the electronic configuration of Al3+. How many electrons are present in its outer most shells
Answer: 732
732-861
Al3+ = 1s2 ,2s2 ,2p6
Question: 733
Define electrochemistry .
Answer: 733
733-861
Electrochemistry is a branch of chemistry that deals with the relationship between electricity and chemical reaction
Question: 734
Why metallic character decrease along a period and increase in a group?
Answer: 734
734-861
Along the period: Metallic character decreases along the period from left to right.
Reason:
1:. From left to right size of atom decreases and nuclear charge increases so is difficult to remove electron and electropositivity decreases.
Question: 735
What do you mean by horticulture and how it is related agriculture ?
Answer: 735
735-861
It deals with the art of gardening . A horticulture works fir the betterment of existing varieties and for the production of new varieties of ornamental plants and fruits plants
Question: 736
Write chemical reaction of H2 with F2 and Cl2 .
Answer: 736
736-861
Reaction of H2 with F2: Flourine combines with hydrogen even in the dark and cold state
H2 +F2➜ 2HF
Question: 737
Calculate the oxidation number of nitrogen in HNO3 .
Answer: 737
737-861
HNO3 = (1) +(N) +3 (-2)
= 1+N-6
N = +5
Question: 738
What is free radical ? Give example.
Answer: 738
738-861
Free radical : Free radical are atoms or groups of atoms possessing odd number (unpaired ) electrons.
Question: 739
Write chemical reaction of water with bromine .

Answer: 739
739-861
bromine only reacts with water under following special condition .
Br2 + H2O ➜ HBr + HOBr

Question: 740
Name a metal which can be cut with knife?
Answer: 740
740-861
Sodium is that metal which can be cut with knife, because it is soft.
Question: 741
Calculate the oxidation number of Sulphur (S) in H2SO4
Answer: 741
741-861
H2SO4 = 2(+1) +(S) +4(-2)
=2=S-8
S = +6
Question: 742
The atomic symbol of a phosphorous ion is given as 3115P3-
a : How many protons , electrons , and neutrons are there in ion3115P3- ?
b: What is the name of ion ?
c:Draw electronic configuration of ion .
d: Name noble gas which has some electronic configuration as phosphorous ?
Answer: 742
742-861
Proton = 15
Electron = 18
Neutron = 16
b: Phosphorous ion
c: E.C =1s2 , 2s2 , 2p6 , 3s2 ,3p6
Question: 743
Which compounds of halogens are stable ?
Answer: 743
743-861
Halogens form very stable compounds with alkali metals
Question: 744
Describe the chemical reaction of alkaline earth metals with hydrogen .
Answer: 744
744-861
Alkaline metals :
Reaction with oxygen :
1: Alkaline metals immediately tarnish in air giving their oxides which form strong alkalies in water
4Na +O➜ 2Na2 O
Na2 O➜ 2NaOH
2: Reaction with hydrogen :
The form ionic hydrides with H2at high temperature
2Na +H2➜2NaH
Reaction with Halogens :
3: They react violently with halogens at room temperature to give halides
2Na +Cl2➜ 2NaCL
Question: 745
Name the most abundant non- metal in earth's crust?
Answer: 745
745-861
Oxygen has has the highest percentage in earth's crust 47% and oceans 86% but second highest percentage in atmosphere 21%
Question: 746
What was the thickness of gild foil used in Rutherford's atomic model ?
Answer: 746
746-861
0.00004 cm thick gold foil was used by Rutherford in his experiment
Question: 747
Do you know any element having no neutron in its atom ?
Answer: 747
747-861
Isotope of hydrogen , protium have one proton and no neutrons in it
Question: 748
What observations were the observations made by Rutherford ?
Answer: 748
748-861
There were two observations .
Question: 749
State the nature and name of the substance formed by combining the following
1: Zinc + Copper
2: Water +Sugar
3: Aluminum +Sulphur
4: Iron + Chromium + Nickle
Answer: 749
749-861
2: Water + Sugar
It will be a solution or mixture called sugar syrup
Question: 750
What are difference between string and weak electrolytes .
Answer: 750
750-861
Strong electrolyte : The substance which ionizes completely in solution to produce more ions which can conduct strongly is called strong electrolyte
Question: 751
Define empirical formula and give example .
Answer: 751
751-861
It is the simplest whole number , ratio of atoms present in a compound
Question: 752
Why the second ionization energy of magnesium is higher than the first one?
Answer: 752
752-861
he l ionization energy of magnesium is high but the 2" ionization energy of magnesium i, very high. It becomes very difficult to remove second electron from the Mg' ion as nuclear charge attracts the remaining electrons strongly. As a result of this attraction size of the ion decreases.
Question: 753
Give few properties of canal rays .
Answer: 753
753-861
a: Deflection of these rays in electric and magnetic field proved that these were positively charged

Question: 754
Write difference between electrolytic cell and galvanic cell.
Answer: 754
754-861
Electrolytic cell :
1: It consists of one complete cell. connected to battery
2: Anode has positive charge while cathode have negative charge
3: Electrical energy is converted into chemical energy
4: Current is used for the non-spontaneous chemical reaction to take place
Question: 755
What are weak electrolytes? . Give example .
Answer: 755
755-861
The substances which ionize to a small extent when dissolved in water and could not produce more ions are called weak electrolytes
Question: 756
Write down two properties of gold

Answer: 756
756-861
1: Gold is a yellow sift metal
2: It is most malleable and ductile of all the metals
Question: 757
How is platinum used as a catalyst in automobiles and what are advantages of this use?
Answer: 757
757-861
An alloy of platinum. palladium and rhodium is used as catalyst in automobiles as catalytic converter. It converts most of the toxic gases (CO, NO2) being emitted by vehicles into less harmful carbon dioxide. nitrogen and water vapour.
Question: 758
What does mean rusting of iron ?
Answer: 758
758-861
Corrosion of iron is called rusting . The important condition for rusting is moist air
Question: 759
What was the pressure inside the discharge tube in discovery of electron?
Answer: 759
759-861
The pressure inside the tube was kept 10-4 atm
Question: 760
Differentiate between homoatomic and heteroatomic molecules with examples .
Answer: 760
760-861
Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
Question: 761
Why do non-metals accept electron readily ?

Answer: 761
761-861
Non-metals have high electronegativity , can accept electrons readily in order to complete their last (valence ) shells

Question: 762
What is difference between valency and oxidation ?
Answer: 762
762-861
Valency : Valency is the combining capacity of an atom with other atoms . It depends upon the number of electrons in the outermost shell
Question: 763
Write any two rules for assigning oxidation number .
Answer: 763
763-861
1: The oxidation number (O.N) of an ion consisting on a single element is the same as the charge on that ion .
Question: 764
Where do electrons flow from Zn electrode in Daniel's cell ?
Answer: 764
764-861
In Daniel's cell electron flow from Zn electrode to Cu electrode i-e from anode to cathode through external circuit
Question: 765
In what conditions H2 reacts with l2 ? Give equation of the reaction .
Answer: 765
765-861
H2 reacts with l2 on heating and in the presence of catalyst to produce hydrogen iodide
H2 + l2 ➜ 2Hl

Question: 766
Give the composition of earth crust with respect to three major elements .
Answer: 766
766-861
Earth crust is formed by three major elements having following percentages
Question: 767
How iron is prevented from rust by tin coating ?
Answer: 767
767-861
1:It involves the dipping of the clean sheet of iron in a bath of molten tin and then passing it through hot rollers
Question: 768
Identify a strong and weak electrolyte among the following compound
  • CuSO4 , Ca (OH)2 , HCL , HNO3
Answer: 768
768-861
Strong electrolyte :HCL ,HNO3 AND CuSO4 are strong electrolyte
Question: 769
Define relative atomic mass .
Answer: 769
769-861
Relative atomic mass of an element is the average masses of atoms of that element as compared to 1 / 12th the mass of one atom of carbon -12 isotope
Question: 770
What is quantum ?
Answer: 770
770-861
Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation
Question: 771
Name one solid , one liquid and one gaseous element present at room temperature ?
Answer: 771
771-861
Sodium ( Na) , Iron ( Fe)
Question: 772
Identify strong or weak electrolyte among the following
CuSO4 , H2CO3 ,(OH)2 , AGNO3 , Ca (OH)2
Answer: 772
772-861
Strong electrolyte :HCL,HNO3 and CuSO4. AgNO3 are strong electrolyte
Question: 773
Define corrosion ?
Answer: 773
773-861
Corrosion is slow and continuous eating away a metal by the surrounding medium . It is a redox chemical reaction that takes place by the action of air and moisture with metals
Question: 774
Write down the reaction occuring on cathode and anode during the electrolysis of water .
Answer: 774
774-861
Following reactions occur at anode and cathode during electrolysis of water
Question: 775
What is galvanic cell? Give an example .
Answer: 775
775-861
The electrochemical cell in which a spontaneous chemical reaction takes place and generates electric current is called galvanic or voltaic cell
Question: 776
What is matter ?
Answer: 776
776-861
Anything which has mass and occupy space is called matter
Question: 777
How galvanizing of iron sheets is done ?
Answer: 777
777-861
The process of Galvanizing is carried out by dipping a clean iron sheet in a zinc chloride bath and then heating it . After this iron sheet is removed , rolled into molten zinc metal bath and finally air -cooled . Advantages of galvanizing is that zinc protects the iron against corrosion
Question: 778
Why sodium metal is more reactive than magnesium ?
Answer: 778
778-861
Magnesium is harder then sodium because density of sodium is 0.98cm -3 and density of magnesium is 1.74gcm3 . Sodium is too soft to be cut with knife
Question: 779
Which metal is used for the galvanizing of iron ?
Answer: 779
779-861
Zinc metal is used for galvanizing of iron because it protects from corrosion
Question: 780
Which one has more formula units : 1g of NaClor 1 g KCL ?
Answer: 780
780-861
NaCl has more formula units than KCl
For NaCl
Formula unit = Mass / Formula mass
= 1/58.5
= 0.017
Question: 781
Write chemical reaction that takes place during working of Nelson's cell.
Answer: 781
781-861
Following reactions take place in Nelson's cell
Ions formed in Brine
2NaCl (aq)➜ 2Na+ (aq) +2Cl(aq)
Question: 782
Name the metal which is least conductor of heat ?
Answer: 782
782-861
Lead is a metal which is least conductor of heat
Question: 783
Differentiate between ions and free radicals ?
Answer: 783
783-861
Ions :
1: These are atoms which bear some charge
2: They exists in solution or in crystal lattice
3: Their formation is not affected by the presence of light
Question: 784
Which solution is used as an electrolyte in Nelson's cell ?
Answer: 784
784-861
In Nelson cell concentrated solution of sodium chloride is used . It is called brine solution
Question: 785
What is relation between electropositivity and ionization energy ?
Answer: 785
785-861
Electropositivity is the reverse of the ionization energy . In the from from top to bottom ionization energy decreases and electropositivity increases
Question: 786
Which term is used to represent the mass of 1 mole of molecules of a substance ?
Answer: 786
786-861
Gram molecular mass
Question: 787
What is the principle of electroplating ?
Answer: 787
787-861
Principle of electroplating is to establish an electrolytic cell in which anode is made of the metal to be deposited and cathode of the object on which metal is to deposit . The electrolyte is an aqueous solution of salt of the respective metal
Question: 788
Give the reaction of mangnesium with O2 And N2 .
Answer: 788
788-861
Reaction of magnesium with O2 :
They are less reactive towards oxygen and oxides are formed on heating
2Mg + ➜ 2MgO
Question: 789
What is stainless steel?
Answer: 789
789-861
Stainless steel is an alloy which is formed by the combination of iron , ,chromium and nickel
Question: 790
How can you justify that air is a homogenous mixture . Identify substance present in it ?
Answer: 790
790-861
Air is a mixture formed by the physical mixing of the substance like nitrogen , oxygen ,carbon dioxide , noble gases and moisture and it has same composition throughout , so it is homogenous mixture
Question: 791
What is metallic coating ?
Answer: 791
791-861
For the protection against the rusting metals are coated with other metal and it is called metallic coating.
Question: 792
Write uses of magnesium .
Answer: 792
792-861
1: Magnesium is used in flash light bulbs and in fireworks .
Question: 793
Differentiate between molecular mass and formula mass, which of the following will be molecular formula?
Answer: 793
793-861
H2O,NaCl, KI, H2SO4
Question: 794
How many atoms are in 1 amu and 1g of hydrogen (H)?
Answer: 794
794-861
1amu and 1 gram of hydrogen (H) has 6.022x1023 atoms and 8 grams of sulphur has 1.005x1023atoms
Question: 795
Differentiate between homoatomic and heteroatomic molecules with example.
Answer: 795
795-861
Homoatomic molecules; A molecule containing same type of atoms is called monatomic molecule.
for example: H2, O3, S8
Question: 796
How platinum is used as a catalyst in automobiles?

Answer: 796
796-861
Platinum and rhodium are used as catalyst convertor
Advantages : They convert most of the gases being emitted by vehicles into less harmful carbon dioxide , nitrogen and water vapour

Question: 797
Why does 10 g nitrogen gas contain the same number of molecules as 10g of carbon monoxide ?
Answer: 797
797-861
Number of moles of nitrogen gas = 10/28 =0.35mol
Number of molecules of N2 = 0.35x0.22x1023
=2.107x1023
Question: 798
Differentiate between molecule or molecular ion ?
Answer: 798
798-861
Molecule :
1: It is the smallest particle of a compound which can exist independently and shows all the properties of that compound
2: It is always neutral
3: It is formed by the combination of atoms
4: It is a stable unit
Question: 799
Which metals are the most malleable and ductile ?
Answer: 799
799-861
Gold (Au) is the most malleable and ductile of all metals . One gram of gold can be drawn into a wire of one and called ductile
Question: 800
Compare two physical properties of metals and non-metals .
Answer: 800
800-861
Metal :
1:Almost all metals are solid (except mercury) they have high densities
Question: 801
Which branch of chemistry deals with the structure and properties of naturally occurring molecules ?
Answer: 801
801-861
Organic chemistry deals with the structure and properties of naturally occurring molecules
Question: 802
How many atoms of sodium are present in 3 moles of sodium and what is the mass of it ?
Answer: 802
802-861
Number of atoms of sodium are present in 3 moles = 3x6.02x1023 atoms
= 1.806x 1024
Question: 803
Complete and balance the given chemical equation Na + H2➜ ?
Answer: 803
803-861
2Na + H2➜ 2NaH
(Sodium ) (Hydrogen ) (sodium hydroxide )
Question: 804
Write reaction of chlorine with hydrogen and water
Answer: 804
804-861
Reaction of hydrogen with chlorine
Cl2 +H2O ➜ HCL +HOCL
Question: 805
Give few properties of cathode rays .
Answer: 805
805-861
a: These rays travel in a straight line perpendicular to the cathode surface
Question: 806
What are metalloides ? Gibe two examples
Answer: 806
806-861
The elements have characteristics of both metals and non-metals are called metalloids
Question: 807
How metallic character is changes in a group of periodic table ?
Answer: 807
807-861
Metallic character increase in a group from top to bottom due to increase in the size of atoms
Question: 808
What will be the nature of charge on an atom when it loses an electron or when it gains an electron ?
Answer: 808
808-861
When it lose an electron it become positive an when it gains and electron it become negative
Question: 809
Complete and balance the following equation Mg +N2➜ ?
Answer: 809
809-861
3Mg +N2➜ Mg3N2
(Magnesium ) (Nitrogen) (Magnesium nitride)
Question: 810
Which branch of chemistry deals with energy of atoms and its uses in daily life ?
Answer: 810
810-861
Nuclear chemistry deals with energy of atoms and its uses in daily life
Question: 811
Write down the chemical reactions of chlorine with hot and cold aqueous solutions of sodium hydroxides
Answer: 811
811-861
Chlorine reacts with cold dilute NaOH to give sodium hypochlorite .
2NaOH +Cl2➜ NaCl+ NaOCL +H2O
Question: 812
Define atom according to Dalton ?
Answer: 812
812-861
Atom is an indivisible , hard ,dense and sphere
Question: 813
How was it is proved that whole mass of an atom is located at its center ?
Answer: 813
813-861
The complete rebounce of a few particles show that the nucleus is very hard , dense and contain all mass of an atom
Question: 814
Magnesium has electronic configuration 2,8,2
a: How many electrons are in outermost shell ?
b: In which sub-shell of outermost shell electrons are present ?
c: Why magnesium tends to lose electron ?
Answer: 814
814-861
a: There are two electrons in outermost shell
b : In sub-shell of outermost shell electron are present
1s2 , 2s2 , 2p6 .3s2
Question: 815
Write four physical properties of calcium metals .
Answer: 815
815-861
1: Calcium is silvery grey and fairly harder metal
Question: 816
Why alkali metals are extremenly reactive ?
Answer: 816
816-861
Alkali metals : The elements in the first group of the periodic table are calleed alkali metals
Reactive of alkali metals :
Alkali metals are extrmely reactive elements because of their ns 1 valence shell electronic configuration . These metals only have one electronin theor valence shell , which can be easily
given out
Question: 817
Define atomic mass unit . Why is it needed ?
Answer: 817
817-861
The unit for relative , atomic mass unit
Question: 818
Why does reactivity of metals increase down the group?
Answer: 818
818-861
The reactivity of metals increase down the group due to increase in atomic size and shielding effect down the group . The ability of the metals to loose electrons increase down the group and ionization energy also decrease hence their reactivity increase down the group
Question: 819