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Question: 1
What is the application of Inorganic Chemistry?
Answer: 1
1-861It has application in every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 2
Define atomic mass unit. Why is it needed?
Answer: 2
2-861Atomic 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: 3
What are the uses of Nuclear Chemistry?
Answer: 3
3-861It has vast application in medical treatment, preservation of food and generation of electrical power through nuclear reactors.
Question: 4
Name one solid, one liquid and one gaseous element present at room temperature?
Answer: 4
4-861Solid : Sodium, Iron
Liquid: Bromine and Mercury
Gas: Oxygen , Nitrogen, and Chlorine
Question: 5
Define Relative atomic mass?
Answer: 5
5-861"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: 6
Define Industrial Chemistry and Analytical Chemistry.
Answer: 6
6-861Industrial 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: 7
Give the composition of Earth Crust with respect to three major elements.
Answer: 7
7-861Earth Crust is formed by three major elements having following percentages.
Oxygen 47%
Silicon 28%
Aluminum 7.8%
Question: 8
How can you justify that air is a homogeneous mixture. Identify substances present in it?
Answer: 8
8-861Air 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: 9
Define Empirical formula and give examples.
Answer: 9
9-861"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: 10
Define Chemistry?
Answer: 10
10-861The Branches of Science which deals with the composition, structure, properties and reactions of matter is called chemistry.
Question: 11
What is the significance of the symbol of an elements?
Answer: 11
11-861Significance 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: 12
On the basis of properties, elements are divided into which groups?
Answer: 12
12-861On the basis of properties elements are divided into metals, non-metal, and metalloids
Question: 13
What is the relationship between atomic number and atomic mass?
Answer: 13
13-861The 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: 14
What is meant by variable valency?
Answer: 14
14-861Some 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: 15
Find out the mass of 3 moles of oxygen atoms.
Answer: 15
15-8613 x 16 = 48 g of oxygen are present in 3 moles.
Question: 16
Why atomic mass of an atom is defined as relative atomic mass?
Answer: 16
16-861ATomic 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: 17
is the mass of 1 mole of Oxygen and 1 mole of Sulphur same.
Answer: 17
17-861No, the mass of 1 mole of oxygen and 1 mole of sulphur atom is not same.
Question: 18
Is atomic mass unit a SI unit of an atomic mass?
Answer: 18
18-861Yes , Atomic mass unit is SI unit of atomic mass.
Question: 19
What is atomic number, how it is represented?
Answer: 19
19-861"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: 20
Which term is used to represent the mass of 1 mole of molecules of a substance?
Answer: 20
20-861Gram molecular mass
Question: 21
What is teh relationship between mass and mole of a substance?
Answer: 21
21-861The relationship between mass and mole of substance is given as following mass of substance = No of moles x Molar mass of substance
Question: 22
What are application of inorganic chemistry.
Answer: 22
22-861It has application is every aspect of chemical industry such as glass, cement, ceramics and metallurgy.
Question: 23
Define empirical formula and give examples.
Answer: 23
23-861It is the simplest whole number , ratio of atoms present in a compound."
Empirical formula of benzene
Empirical formula of Hydrogen peroxide
Question: 24
What is Radical?
Answer: 24
24-861An 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
25-861The combining capacity of an element with other elements is called valency
For example. Valency of carbon is 4
Question: 26
How many atoms are present in one gram atomic mass of a substance?
Answer: 26
26-861One gram atomic mass of a substance is equal to Avogadro's number in which 6.023 x 1023 atoms are present
Question: 27
How many atoms are present in 16 g of O and 8g of S?
Answer: 27
27-86116 grams of oxygen has 6.022 x 1023atoms and 8 grams of sulphur has 1.055x1023atoms.
Question: 28
Define industrial chemistry and analytical chemistry
Answer: 28
28-861Industrial 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: 29
What is free radical? Give example.
Answer: 29
29-861"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: 30
What is radical
Answer: 30
30-861An 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: 31
What is the relationshp between atomic number and atomic mass?
Answer: 31
31-861The relation between atomic number and atomic mass is as following A = Z + n
Question: 32
How many atoms are in I amu and I g of hydrogen .
Answer: 32
32-8611 amu and 1 gram of hydrogen has 6.022x1023 atoms.
Question: 33
Define Biochemistry.
Answer: 33
33-861"It is branch of chemistry in which we study the structure, composition and chemical reactions of substances found in living organisms .
Question: 34
Write down chemical reaction of sodium with H2 and Cl2 .
Answer: 34
34-861Reaction of hydrogen with sodium :
Sodium reacts with hydrogen at high temperature to form hydrides
2 Na + H2➜ 2NaH
Question: 35
In which branch of chemistry behaviour of gases and liquid is studied?
Answer: 35
35-861The behaviour of gases and liquids is studied in the branch of chemistry called physical chemistry.
Question: 36
If 16 gram of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams.
Answer: 36
36-86116 g of oxygen = 1 mole of oxygen
Mass of one atom of oxygen = 16 grams.
Question: 37
Write chemical reaction of H2 with F2 and Cl2 .
Answer: 37
37-861Reaction of H2 with F2: Flourine combines with hydrogen even in the dark and cold state
H2 +F2➜ 2HF
Question: 38
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: 38
38-8611:Zinc + Copper
It will be a mixture called a brass (alloy)
Question: 39
Which branch of chemistry deals with preparation of paints and papers?
Answer: 39
39-861"Industrial chemistry deals with preparation of paints and papers."
Question: 40
What is the relationship between empirical formula and formula unit.
Answer: 40
40-861All the organic compounds are represented by formula unit. Formula unit is also and empirical formula of Ionic compounds.
Question: 41
What do you mean by 1 atom carbon and 1 gram atom of Carbon.
Answer: 41
41-861One 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: 42
How many times is 1 mole of oxygen atom heavier than 1 mole of hydrogen atom?
Answer: 42
42-861One mole of oxygen atom is 16 times heavier than the one mole of hydrogen.
Question: 43
Which branch of chemistry deals with energy of atoms and its uses in daily life.
Answer: 43
43-861Nuclear chemistry deals with energy of atoms and its uses in daily life.
Question: 44
Give the composition of milk.
Answer: 44
44-861Milk is a mixture of calcium , water, sugar, fat, proteins, minerals, salts and vitamins.
Question: 45
Classify the following into elements , compound and mixture ?
1: He and H2
2: CO and Co
3: Water and milk
4: Gold and brass
5: Iron and steel
Answer: 45
45-861Elements :
He , H2 ,Co, Gold , Iron
Question: 46
Write down the chemical reactions of chlorine with hot and cold aqueous solutions of sodium hydroxides
Answer: 46
46-861Chlorine reacts with cold dilute NaOH to give sodium hypochlorite .
2NaOH +Cl2➜ NaCl+ NaOCL +H2O
Question: 47
In which branch of chemistry deals with preparation of paints and papers?
Answer: 47
47-861"Industrial chemistry deals with preparation of paints and papers".
Question: 48
In the basis of properties , elements are divided into which group ?
Answer: 48
48-861On the basis of properties elements are divided into metals , non-metals and metalloids
Question: 49
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: 49
49-8612: Water + Sugar
It will be a solution or mixture called sugar syrup
Question: 50
Give the scope of biochemistry .
Answer: 50
50-861It 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: 51
Which branch of chemistry deals with the structure and properties of naturally occurring molecules.
Answer: 51
51-861"Organic chemistry deals with the structure and properties of naturally occuriring molecules."
Question: 52
How can you differentiate between organic and inorganic chemistry .
Answer: 52
52-861Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
Question: 53
What are the uses of nuclear chemistry ?
Answer: 53
53-861It has vast application in medical treatment , preservation of food , and generation of electrical power nuclear reactors
Question: 54
Differentiate between empirical and molecular formula.
Answer: 54
54-861Empirical formula: it is the simplest whole number ratio of atoms present in a compound
e.g. Empirical formula of benzene is CH.
Question: 55
State three reasons why do you thing soft drink is a mixture and water is a compound .
Answer: 55
55-861Soft drink is a mixture because :
1: Its components are not bounded chemically
2: The components do not have fix ratio
Question: 56
Difference between homogeneous and heterogeneous mixture.
Answer: 56
56-861Homogeneous mixture: Mixtures that have uniform composition throughout are called homogeneous mixtures.
example: Milm, Brass, Ice-cream.
Question: 57
Define atomic mass unit . Why is it needed ?
Answer: 57
57-861The unit for relative , atomic mass unit
Question: 58
What is valency ?
Answer: 58
58-861The combining capacity of an element with other element is called valency
Question: 59
Define relative atomic mass .
Answer: 59
59-861Relative 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: 60
Which has more atoms :10g of Al or 10 g of Fe ?
Answer: 60
60-86110 g of A 1 has more atoms than 10 g of Fe
For A 1
Question: 61
How does homogenous mixture differ from heterogenous mixture ?
Answer: 61
61-861Homogenous mixture : Mixtures that have uniform composition through are called homogenous mixture
Question: 62
Give the composition of earth crust with respect to three major elements .
Answer: 62
62-861Earth crust is formed by three major elements having following percentages
Question: 63
Define empirical formula and give example .
Answer: 63
63-861It is the simplest whole number , ratio of atoms present in a compound
Question: 64
State three reasons why do you think air is a mixture and water a compound
Answer: 64
64-861Air (mixture)
1: Mixture is formed by the simple mixing up of the substances
2: Air does not have a sharp and fixed melting point
3: Air has heterogenous mixture composition
Question: 65
Explain why are oxygen and hydrogen considered elements whereas water as a compound ?
Answer: 65
65-861Hydrogen and oxygen are element because
1: Each one of it consists of same type of atoms
Question: 66
Differentiate between atom and ion ?
Answer: 66
66-861Atom :
1: It is the smallest particle of an element
2: It can or cannot exists independently and can take part in a chemical reaction
3: It is electrically neutral
Question: 67
Differentiate between molecular mass and formula mas , which of the following is molecular formula ?
. H2O
.NaCl
.Kl
.H2SO4
Answer: 67
67-861Molecular mass :
The sum of atomic masses of all the atoms present in one molecule of a molecular compound is its molecular mass
Question: 68
Differentiate between substance and mixture .
Answer: 68
68-861Substance : A piece of matter in pure form is termed as substance
e,g Glucose (C6H12O6 ) Oxygen
Question: 69
What are applications of inorganic chemistry?
Answer: 69
69-861It has application in every aspect of chemical industry such as glass , cement , ceramics and metallurgy
Question: 70
How many atoms are present in one gram atomic mass of a substance ?
Answer: 70
70-861One gram atomic mass of a substance is equal to Avogadro's number in which 6.023x1023atoms are present
Question: 71
Which one has more formula units : 1g of NaClor 1 g KCL ?
Answer: 71
71-861NaCl has more formula units than KCl
For NaCl
Formula unit = Mass / Formula mass
= 1/58.5
= 0.017
Question: 72
What is matter ?
Answer: 72
72-861Anything which has mass and occupy space is called matter
Question: 73
Which of the following cases the number of hydrogen atoms is more?
Answer: 73
73-8611 mole of NH3 has more hydrogen atoms than 2 moles of HCL
Question: 74
Give the composition of milk .
Answer: 74
74-861Milk is a mixture of calcium , water ,sugar , fat , proteins , minerals, salts , and vitamins
Question: 75
Identify the following as empirical or molecular formula :
H2O2 ,CH4 , C6H12O6 , C12H22O11 ,BaCO3 ,KBr
Answer: 75
75-861Empirical formula : KBr , BaCO3 , CH4
Question: 76
Define chemistry ?
Answer: 76
76-861The branch of science which deals with the composition , structure , properties and reactions of matter is called chemistry .
Question: 77
Which one has more molecules : 9 g of water or 9 g of sugar C12 H22 O11 ?
Answer: 77
77-8619g of water has more molecules than 9 g of sugar because moles of water are more than sugar
For water
Question: 78
Which six elements constitute 99% of body mass and what are their percentages ?
Answer: 78
78-861Following six elements constitute 99%of body mass
Oxygen 65%
Hydrogen 10%
Calcium 1.5 %
Carbon 18%
Nitrogen 3%
Phosphorous 1.5%
Question: 79
Write any two applications of inorganic chemistry.
Answer: 79
79-861Inorganic chemistry has applications in following aspects of the chemistry industry
Question: 80
Differentiate between homoatomic and heteroatomic molecules with examples .
Answer: 80
80-861Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
Question: 81
Differentiate between empirical and molecular formula .
Answer: 81
81-861Empirical formula: It is the simplest whole number ratio of atoms present in a compound
Question: 82
Is atomic mass unit a SI unit of an atomic mass ?
Answer: 82
82-861Yes ,atomic mass unit is SI unit of atomic mass
Question: 83
In which branch of chemistry behaviour of gases and liquid is studied ?
Answer: 83
83-861The bahaviour of gases and liquid is studied in the branch of chemistry called physical chemistry
Question: 84
How can you justify that air is a homogenous mixture . Identify substance present in it ?
Answer: 84
84-861Air 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: 85
What elements do the following compound contains ?
Answer: 85
85-861Sugar ,common salt , lime water and chalk
Question: 86
Which term is used to represent the mass of 1 mole of molecules of a substance ?
Answer: 86
86-861Gram molecular mass
Question: 87
Write down the name of any two elements which were discovered in early ages .
Answer: 87
87-861Following elements were discovered in early ages
Question: 88
What is radical ?
Answer: 88
88-861An 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: 89
What is meant by variable valency ?
Answer: 89
89-861Some elements show more than one combining power (valency) that is called variable valency
Question: 90
What is the atomic number , how it is represented ?
Answer: 90
90-861The atomic number of an element is equal to the number of protons present in the nucleus of its atoms
Question: 91
Define chemistry ? Explain two branches of chemistry .
Answer: 91
91-861Chemistry : The Branch of science which deals with the composition , structure, properties and reaction of matter is called chemistry
Question: 92
Differentiate between homogenous and heterogenous mixture .
Answer: 92
92-861Homogenous Mixture : Mixtures that have have uniform composition throughout are calledhomogenous mixture
Question: 93
If 16g of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams
Answer: 93
93-86116g of oxygen =1 mol of oxygen
Mass of one atom of oxygen = 16 grams
Question: 94
Name one solid , one liquid and one gaseous element present at room temperature ?
Answer: 94
94-861Sodium ( Na) , Iron ( Fe)
Question: 95
Find out molecular mass and formula masses of the following
Na2SO4 ,ZnSO4 , and CuCO3.
Answer: 95
95-861Formula mass of Na2SO4 = 2(23)+32+4 (16)
= 46+32+64
=142 amu
=142 amu
Question: 96
Why atomic mass of an atom is defined as relative atomic mass ?
Answer: 96
96-861Atomic 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: 97
Differentiate between molecule or molecular ion ?
Answer: 97
97-861Molecule :
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: 98
How many amu 1 g of a substance has ?
Answer: 98
98-8611.66x 10-24g +1 amu
1g = 1/1.66x 10-24amu
Question: 99
Why does 10 g nitrogen gas contain the same number of molecules as 10g of carbon monoxide ?
Answer: 99
99-861Number of moles of nitrogen gas = 10/28 =0.35mol
Number of molecules of N2 = 0.35x0.22x1023
=2.107x1023
Question: 100
Define matter and mixture .
Answer: 100
100-861Matter : anything that has mass and occupies space is called matter . Matter exists in three physical states , solid , liquid , gas
Question: 101
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: 101
101-861Proton = 15
Electron = 18
Neutron = 16
b: Phosphorous ion
c: E.C =1s2 , 2s2 , 2p6 , 3s2 ,3p6
Question: 102
Define organic chemistry and which industries covered by it
Answer: 102
102-861Organic chemistry : it is the study of covalent compounds of carbon and hydrogen and its derivatives
Question: 103
What is the relationship between mass and mole of a substance ?
Answer: 103
103-861the relationship between mass and mole of a substance is given as following
Question: 104
Define Biochemistry ? Describe scope of biochemistry and give two examples of biochemistry.
Answer: 104
104-861The branch of science concerned with the chemical and physico-chemical processes and substances that occur within living organisms.
Question: 105
Write difference between physical and chemical properties .
Answer: 105
105-861Chemical 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: 106
Explain difference between physical chemistry and biochemistry .
Answer: 106
106-861Physical 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: 107
What is the relationship between atomic number and atomic mass ?
Answer: 107
107-861The relationship between atomic number and atomic mass is as following
A = Z+n
Where A = mass number
Z = atomic number
N = no of electrons
Question: 108
Find out the mass of 3 moles of oxygen atoms .
Answer: 108
108-8613x16 = 48g of oxygen are present in 3 moles
Question: 109
What is the significance of chemical formula ?
Answer: 109
109-8611: It represents the name of the substance e.g H2O (water)
Question: 110
How many atoms of hydrogen present in 1 mole of water ?
Answer: 110
110-8611 mole of water = 6.02 x 1023molecules
1 mole of water has H atom =1x 6.02x1023atoms
= 6.02 x 1023
Question: 111
Differentiate between ions and free radicals ?
Answer: 111
111-861Ions :
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: 112
Define industrial chemistry and analytical chemistry ?
Answer: 112
112-861Industrial chemistry : It is the branch of chemistry that deals with the manufacturing of chemical compounds on commercial scale
Question: 113
How many times is 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams
Answer: 113
113-861One mole of oxygen atom is 16 times heavier than the one mole of hydrogen
Question: 114
What do you mean by 1 atom of C and 1 gram of atom of C ?
Answer: 114
114-861One 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: 115
Differentiate between nuclear chemistry and environmental chemistry .
Answer: 115
115-861Environmental 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: 116
Differntiate between biochemistry and industrial chemistry .
Answer: 116
116-861Biochemistry : Biochemistry is the branch of chemistry in which w study the structure , composition , and chemical reaction of substances found in living organisms
Question: 117
How many atoms of sodium are present in 3 moles of sodium and what is the mass of it ?
Answer: 117
117-861Number of atoms of sodium are present in 3 moles = 3x6.02x1023 atoms
= 1.806x 1024
Question: 118
What was the pressure inside the discharge tube in discovery of electron?
Answer: 118
118-861The pressure inside the tube was kept 10-4 atm
Question: 119
Give few properties of cathode rays .
Answer: 119
119-861a: These rays travel in a straight line perpendicular to the cathode surface
Question: 120
How many atoms are present in 16g of Oand of S ?
Answer: 120
120-86116 grams of oxygen has 6.022x1023atoms and 8 grams of sulphur has 1.055x1023 atoms
Question: 121
Which branch of chemistry deals with preparation of paints and papers ?
Answer: 121
121-861Industrial chemistry deals with preparation of paints and papers .
Question: 122
Define biochemistry ?
Answer: 122
122-861It 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: 123
A long as electron remains in an orbit , it does not emit or absorb energy , when does it emit or absorb energy ?
Answer: 123
123-861When an electron jumps from lower orbit to higher orbit . It absorbs energy and when it jumps from higher orbit to lower orbit . It radiates energy . This change in energy ,
| △E given by following Plank's equation |
Question: 124
How many molecules of water are present in half mole of water ?
Answer: 124
124-861Water molecules in half moles = 1/2x6.02x1023
= 3.01x1023 molecules
Question: 125
Write name of any two elements found in gaseous state
Answer: 125
125-861Nitrogen and oxygen both found in gaseous state
Question: 126
What is the nature of charge on cathode rays ?
Answer: 126
126-861Their deflection in electric and magnetic field proves that they have negative charge
Question: 127
What is meant by element ? Explain with example .
Answer: 127
127-861Element 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: 128
Is the mass of 1 mole of O and 1 mole of S same ?
Answer: 128
128-861Nothe mass of 1 mole of O and 1 mole of S is not same
Question: 129
What is free radical ? Give example.
Answer: 129
129-861Free radical : Free radical are atoms or groups of atoms possessing odd number (unpaired ) electrons.
Question: 130
Which branch of chemistry deals with energy of atoms and its uses in daily life ?
Answer: 130
130-861Nuclear chemistry deals with energy of atoms and its uses in daily life
Question: 131
How many atoms are in 1 amu and 1g of hydrogen (H)?
Answer: 131
131-8611amu and 1 gram of hydrogen (H) has 6.022x1023 atoms and 8 grams of sulphur has 1.005x1023atoms
Question: 132
Define atom according to Dalton ?
Answer: 132
132-861Atom is an indivisible , hard ,dense and sphere
Question: 133
What is the relationship between empirical formula and formula unit ?
Answer: 133
133-861All the ionic compounds are represented by formula unit . Formula unit is also and empirical formula of ionic compounds
Question: 134
Define electronic configuration ?
Answer: 134
134-861Electronic configuration : The distribution of electrons around the nucleus in various shells and sub-shells according to increasing energy , is called electronic configuration
Question: 135
What are shells ?
Answer: 135
135-861Shells are specific energy levels around nucleus in which electron resolve
e.g K,L,M,N
Question: 136
In which branch of chemistry are the metabolic processes of carbohydrates and proteins studied ?
Answer: 136
136-861In biochemistry metabolic processes carbohydrates and proteins are studied
Question: 137
From which word atom derived ?
Answer: 137
137-861Atom is derived from latin word 'Atomos' meaning indivisible
Question: 138
Name the elements represented by the following symbols W, Ba , Hg and Na
Answer: 138
138-861Tungsten W , Barium B , Mercury Hg , Sodium Na
Question: 139
An element has an atomic number 17 , how many electrons are present in K and M shells of an atom ?
Answer: 139
139-861K=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: 140
Differentiate shell and sub-shell with example of each ?
Answer: 140
140-861Shell (Orbit):
The circular orbits of specific energy are called shells or energy levels
Question: 141
What is the empirical formula of acetic acid (CH3COOH)? Also calculate the molecular mass of acetic acid .
Answer: 141
141-861Empirical formula of acetic acid is CH2O
Question: 142
Give few properties of canal rays .
Answer: 142
142-861a: Deflection of these rays in electric and magnetic field proved that these were positively charged
Question: 143
Which branch of chemistry deals with the structure and properties of naturally occurring molecules ?
Answer: 143
143-861Organic chemistry deals with the structure and properties of naturally occurring molecules
Question: 144
What is the capacity of the K,L,M,N shells ?
Answer: 144
144-861K shell can accommodate 2 electron
L shell can accommodate 8 electrons
M shell can accommodate 18 electrons
N shell accommodate 32 electrons
Question: 145
Write any two elements found in the liquid state at room temperature .
Answer: 145
145-861Mercury and bromine are two elements found in the liquid state at room temperature
Question: 146
For what purpose U-235 is used ?
Answer: 146
146-861When U-235 is bombarded with slow moving neutrons , uranium nucleus breaks up to produce Barium-139 and Krypton -94 and three neutrons
Question: 147
What is classical theory of radiation . How it is differ from quantum theory ?
Answer: 147
147-861According 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: 148
What is the capacity of shells ?
Answer: 148
148-861The number of electrons accommodated by the shell called capacity of shell
Question: 149
Which carbon isotope use in carbon dating ?
Answer: 149
149-861C-14 used in carbon dating
Question: 150
Do you know any element having no neutron in its atom ?
Answer: 150
150-861Isotope of hydrogen , protium have one proton and no neutrons in it
Question: 151
Difference between molecular mass and formula mass.
Answer: 151
151-861Molecular Mass:
The sum of the atomic mass of all the elements present in a molecule is called as Molecular Mass.
Question: 152
What is the significance of the symbol of an element ?
Answer: 152
152-861Symbol 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: 153
A patient has goiter . How will it be detected ?
Answer: 153
153-861The radioactivity isotopes are used as tracers in medicine to diagnose the presence of tumor in human body . Isotope of I-131 is used for diagnose of goiter in thyroid gland
Question: 154
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: 154
154-861a: There are two electrons in outermost shell
b : In sub-shell of outermost shell electron are present
1s2 , 2s2 , 2p6 .3s2
Question: 155
What was the thickness of gild foil used in Rutherford's atomic model ?
Answer: 155
155-8610.00004 cm thick gold foil was used by Rutherford in his experiment
Question: 156
What is quantum ?
Answer: 156
156-861Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation
Question: 157
What is meant by mixture ? Give example.
Answer: 157
157-861When two or more elements or compounds mix up physically without any fixed ratio they form a mixture
Question: 158
How does homogeneousmixture differ from heterogeneous mixture?
Answer: 158
158-861The mixture that has uniform composition throughout is called homogeneous mixture which composition is not uniform throughout e.g. soil , rock and wood etc.
Question: 159
Explain how anode rays are formed from the gas taken in the discharge tube .
Answer: 159
159-861Anode 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: 160
Write down the electronic configuration of Al3+. How many electrons are present in its outer most shells
Answer: 160
160-861Al3+ = 1s2 ,2s2 ,2p6
Question: 161
Name the particle which determine the mass of an atom ?
Answer: 161
161-861Protons and neutrons determine the mass of an atom
Question: 162
Who discovered proton , electron , neutron ?
Answer: 162
162-861In 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: 163
Why ionic compounds are easy soluble in water?
Answer: 163
163-861Water 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: 164
Human body made up of how many elements ? Write their names .
Answer: 164
164-861Six 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: 165
How many electrons are present in sub-shell ?
Answer: 165
165-861s can have 2 electrons
p can have 6 electrons
d can have 10 electrons
f can have 14 electrons
Question: 166
When do electrons emit or absorb energy ?
Answer: 166
166-861A long as electron remain in a particular orbit it does not radiate or absorb energy, The energy is emitted or absorbed only when an electron jumps from one orbit to another
Question: 167
What will be the nature of charge on an atom when it loses an electron or when it gains an electron ?
Answer: 167
167-861When it lose an electron it become positive an when it gains and electron it become negative
Question: 168
What id meant by atom and ion?
Answer: 168
168-861Atom
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: 169
How was it shown that atomic nuclei are positively charged ?
Answer: 169
169-861The deflection of a few particles proved that there is a center of positive charge in an atom , , which is called nucleus of an atom
Question: 170
How many sub-shells are there in second shells ?
Answer: 170
170-861Two sub-shells s and p are present in second shell L
Question: 171
How is the goiter in thyroid gland detected ?
Answer: 171
171-861Iodine -131 is used fir the diagnosis of goiter in thyroid gland
Question: 172
What observations were the observations made by Rutherford ?
Answer: 172
172-861There were two observations .
Question: 173
Calculate no of carbon atoms in one mole C6 H12 O6
Answer: 173
173-8616 atoms of carbon are present in one mole of glucose
Question: 174
Define isotope ?
Answer: 174
174-861Isotopes are defined as the atoms of elements that have same atomic number but different mass number
Question: 175
Explain any two factors that effect the diffusion .
Answer: 175
175-861Factors effecting in diffusion :
1 :Size of molecules : Big sized molecules diffuse slowly
Question: 176
How was it is proved that whole mass of an atom is located at its center ?
Answer: 176
176-861The complete rebounce of a few particles show that the nucleus is very hard , dense and contain all mass of an atom
Question: 177
What is difference between elements and compound ?
Answer: 177
177-861Compound : Compound is a substance made up of two or more elements chemically combined together in a fixed ratio by mass
Example : Water (H2O)
Question: 178
Why melting point and boiling points of ionic compounds are high?
Answer: 178
178-861Melting 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: 179
How can you prove that angular momentum is quantized ?
Answer: 179
179-861mvr =nh/2π
The angular momentum of first orbit is (n=1)
mvr = 6.63x10-34/2x 3.14
Question: 180
How many neutrons are present in C-12 and C-13 ?
Answer: 180
180-861C-12 C-13
P=6 P=6
N=12-6=6 N=13-6=7
Question: 181
What is atomic number of phosphorous ? Write down its electronic configuration .
Answer: 181
181-861Atomic number of phosphorous (P) is 15
Electronic configuration
1s2 , 2s2 ,2p6 ,3s2 ,3p3
Question: 182
Give some examples of arsenic and silver .
Answer: 182
182-861Symbols of arsenic and silver are as following
Question: 183
Define Boyle's law .
Answer: 183
183-861According to Boyle's law the volume of a given mass of a gas is inversely proportional to its pressure at constant temperature .
Question: 184
Why does an electron fill 2p orbital and then 3s and then 3s orbital ?
Answer: 184
184-861As 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: 185
Define symbol and valency with example .
Answer: 185
185-861Symbol : The representation of any element with one or two english letters is called symbol.
Question: 186
What is mean by cation and anion? Explain with example.
Answer: 186
186-861Cation: Na ______> Na+ + 1e-
The cations are formed when an atom loses electrons from its outmost shells. For example cations are Na + , K+, Ca+ 2
Question: 187
Write the relation between empirical formula and molecular formula
Answer: 187
187-861There is a relationship betweenempirical formula and molecularformula which is given as:
Molecular formula= (empirical formula
Where n= 1, 2, 3,,,,,,
Question: 188
How many electrons will be in M-shell of an atom having atomic number 15 ?
Answer: 188
188-861K L M
2 8 5
5 electrons are present in M shell of an atom having atomic number 15
Question: 189
Give electronic configuration of hydrogen ?
Answer: 189
189-861Electronic configuration of 11H is 1s1
Question: 190
Write two properties of gases
Answer: 190
190-8611: Molecules of gases are always in state of continuous motion . They have very high K.E .
Question: 191
Why do the isotopes of an element have different atomic number masses?
Answer: 191
191-861As 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: 192
Ionic compounds are solids. Explain
Answer: 192
192-861Ionic 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: 193
What is meant by relative molecular mass?
Answer: 193
193-861Relative 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: 194
Write two significance of chemical formula .
Answer: 194
194-8611: it indicates the mass of the compound in amu or grams
Question: 195
Write the percentage of volume by weight of oxygen in atmosphere and oceans
Answer: 195
195-861In atmosphere oxygen is 21% while in oceans it is 86%
Question: 196
Write two properties of ionic compound .
Answer: 196
196-8611: Ionic compound are mostly crystalline solid
Question: 197
Define relative atomicmass based on C-12 scale.
Answer: 197
197-861Relative 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: 198
Write four examples of mixture .
Answer: 198
198-8611: Air is a mixture of nitrogen , carbon dioxide , noble gasses and water vapours
Question: 199
If an element has atomic number 13 and atomic mass 27 , how many electrons are there in each atom of the element?
Answer: 199
199-861Atomic 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: 200
Why the bond between an electropositive and electronegative atom is ionic in nature ?
Answer: 200
200-861Electropositive elements lose electrons while electronegative elements gain electrons . That's why both combine and forms ionic bond
Question: 201
Define element?
Answer: 201
201-861Sodium (Na) and Hydrogen (H) etc
Question: 202
Briefly describe the mobility of gases.
Answer: 202
202-861Gas 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: 203
What is diffusion ? Explain with example .
Answer: 203
203-861Diffusion : 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: 204
What is the valency id following ?
(A) Barium (B) Nitrogen (C) Sodium (D) Sulphur
Answer: 204
204-861Elements valency
1: Barium 2
2: Nitrogen 3
3: Sodium 1
4: Sulphur 2
Question: 205
Why shielding effect of electrons makes action formation easy ?
Answer: 205
205-861As 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: 206
What isAvogadro's number?
Answer: 206
206-861Avogadro, 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: 207
Write any two properties of covalent compounds .
Answer: 207
207-8611: 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: 208
Define ionic bond and ionic compounds .
Answer: 208
208-861Ionic bond : The type of chemical bond which is formed due to complete transfer of electron from one another is called ionic bond
Question: 209
Define atomic mass unit .
Answer: 209
209-861One 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: 210
Why metals are good conductor of electricity ?
Answer: 210
210-861Metals are good conductors of heat and electricity in solid and liquid state due to mobile electrons
Question: 211
What is meant by malleability ?
Answer: 211
211-861Malleabilityis the property by virtue of which a metal can be drawn into sheets
Question: 212
Why the rate of diffusion gases is rapid than that of liquids ?
Answer: 212
212-861The 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: 213
An element has 5 electron in M shell . Find out its atomic number ?
Answer: 213
213-861The number of this element will be 15
Question: 214
Write two properties of covalent compounds
Answer: 214
214-8611: They have usually low melting and boiling points
Question: 215
Whether the density of gases increase on cooling ?
Answer: 215
215-861The density of gases increasing by cooling because their volume decreases and molecules of gases came close to each other
Question: 216
Difference between true solution and colloid solution?
Answer: 216
216-861True solution:Solutions are the homogeneous mixture of two or more than two components.
Question: 217
Write down any two properties of metals .
Answer: 217
217-8611: They show metallic luster
Question: 218
Why drops of rain fall downward?
Answer: 218
218-861The 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: 219
What are meant by coordinate covalent compounds ?
Answer: 219
219-8611: 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: 220
Which are physical properties of matter ?
Answer: 220
220-8611: Matter exists in three physical state i-e gas, liquid , and solid
Question: 221
Define relative atomic mass.
Answer: 221
221-861Relative 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: 222
Define Mendeleev's periodic table ?
Answer: 222
222-861A 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: 223
What is the difference between diffusion and effusion ?
Answer: 223
223-861Diffusion: The spontaneous mixing of molecules by random motion and collision of gases form homogenous mixture is called diffusion
Question: 224
Why volume of gas decreases with increase of pressure ?
Answer: 224
224-861Volume 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: 225
Ionic bond is stronger than covalent bond . Explain .
Answer: 225
225-861Ionic bond formed between two opposite charges and electrostatic forces . That's why ionic compound is stronger than covalent bond
Question: 226
Why cesium (At.No.55 ) requires little energy to release its one electron present in their outermost shell ?
Answer: 226
226-861Cesium 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: 227
Why densities of gases are less than liquids ?
Answer: 227
227-861Gases 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: 228
Write two properties of liquid state of matter
Answer: 228
228-8611: Liquid have fixed volume but no fixed shape . It attains the shape of container in which it is kept
Question: 229
What is difference between compound and mixture / Give example .
Answer: 229
229-861Compound :
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: 230
Convert 560 torr into cmHg
Answer: 230
230-8611 torr = 1mm Hg
Question: 231
What is relative atomic mass ? How is it related to gram ?
Answer: 231
231-861The 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: 232
Define pressure and write its unit .
Answer: 232
232-861Pressure : It is defined as the force exerted by per unit surface area
Question: 233
Which gasses are present in air ? Write their names .
Answer: 233
233-861Oxygen , nitrogen , carbon dioxide , argon are major gasses present in air
Question: 234
Define periods ?
Answer: 234
234-861Seven horizontal rows present in periodic table are called periods . Numbered from 1 to 7
Question: 235
Define effusion . Give example .
Answer: 235
235-861Effusion : Effusion is defined as the escaping of gas molecules through tiny holes into a space with lesser pressure
Question: 236
Define pascal .It is the unit of which quantity ?
Answer: 236
236-861If one newton force is applied on 1m2area then pressure is called one pascal . It is unit of pressure
Question: 237
How is periodicity of properties dependent upon the number of protons in an atom ?
Answer: 237
237-861In 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: 238
Define freezing point ?
Answer: 238
238-861The temperature at which liquid and solid coexist at dynamic equilibrium is called freezing point
Question: 239
Define atomic number and atomic mass .
Answer: 239
239-861Atomic 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: 240
Define homogenous mixture and give example .
Answer: 240
240-861Homogenous mixture: The mixture having uniform composition is calledhomogenous mixture
Question: 241
Define standard atmosphere pressure and write its unit .
Answer: 241
241-861The pressure exerted by a mercury column of 760mm at sea level called standard atmospheric pressure
Question: 242
An element with A = 39 , Z = 19 .Calculate the number of electrons and protons in one atom of this element
Answer: 242
242-861Atomic 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: 243
Why 2nd ionization energy of an elements is higher than first one?
Answer: 243
243-861fins: 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: 244
Why the liquid molecules are mobile ?
Answer: 244
244-861Liquid 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: 245
Is the Boyle's law applicable to liquid ? Give reason .
Answer: 245
245-861No 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: 246
Define nuclear fission reaction .
Answer: 246
246-861A reaction in which heavy nuclear splits up into two nuclei by absorbing show moving next ions
Question: 247
Explain plum pudding theory .
Answer: 247
247-861Thomson 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: 248
Soft drink is a mixture while water is compound . Give the reason .
Answer: 248
248-861Water : Water forms by the chemical reaction of hydrogen and oxygen . that's why it is called compound
Question: 249
Differentiate between molecular mass and formula mass .
Answer: 249
249-861Formula 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: 250
What is matter ? How many states it has ?
Answer: 250
250-861Matter is any thing that has mass and occupies space .
Question: 251
Define groups ?
Answer: 251
251-861The vertical columns in periodic table are called groups . Numbered from 1 to 18
Question: 252
Convert -45°C to kelvin temperature .
Answer: 252
252-861(T)K = (T)°C +273
(T)K = (-45)°C +273
(T)K = (-45+ 273)°C
(T)K = 228
Question: 253
Differentiate between boiling and melting point .
Answer: 253
253-861Melting point : The temperature at which the solid starts melting and exist in dynamic equilibrium with liquid state is called melting point
Question: 254
Define chemical formula and give one examples .
Answer: 254
254-861Definition : A chemical formula is the symbolic representation the elements in the compounds and the ratio of the elements to one another
Question: 255
What is absolute temperature scale ?
Answer: 255
255-861Lord 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: 256
Metals arc good conductor of electricity. Why?
Answer: 256
256-861Metals 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: 257
Define evaporation and give example ?
Answer: 257
257-861Evaporation: The conversion of liquid into vapours called evaporation .
Question: 258
Why do the bigger size atoms have more shielding effect?
Answer: 258
258-861In bigger size atoms the number of inner shells and inner shell electrons increases hence the shielding effect in bigger size molecules also increases.
Question: 259
What is kept constant in Charles law ?
Answer: 259
259-861Pressure is kept constant in Charles law
Question: 260
What is meant by molecular ion ?
Answer: 260
260-861When a molecule loses or gains one or more electron , it forms a molecular ion
Question: 261
Give one example each of the use of radioactive isotope in medicine and radiotherapy ?
Answer: 261
261-861Radioactive isotopes is used in medicine
Iodine 131
Radioactive isotopes used in radiotherapy
P-32
Sr-90
Co-60
Question: 262
Why cesium requires little energy to release its one electron present in the their outermost shell ?
Answer: 262
262-861Cesium 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: 263
In which unit body temperature is measured ?
Answer: 263
263-861Body temperature is measured in fahrenheit scale
Question: 264
Write down the chemical formulas of the following
(a) Sugar (b) Sulphuric acid
Answer: 264
264-861(a) Sugar : C12H22O11
Question: 265
Convert 30°Cto kelvin temperature
Answer: 265
265-861We 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: 266
Write chemical formula of caustic soda and washing soda .
Answer: 266
266-861Caustic soda: NaOH
Question: 267
How is periodicity of properties dependent upon the numbers of protons in an atom ?
Answer: 267
267-861In 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: 268
Define Dynamic equilibrium ?
Answer: 268
268-861When 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: 269
What are Dobereiner's triads ?
Answer: 269
269-861A 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: 270
What is charles law ? Write its equation .
Answer: 270
270-861French 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: 271
What is the difference between Mendeleev's and modern periodic law ?
Answer: 271
271-861Mendeleev's periodic law :
Properties of the element are periodic function of their atomic masses is called Mendeleev's periodic law
Question: 272
What is compressibility?
Answer: 272
272-861Decrease 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: 273
What do you mean by group or median in periodic table ?
Answer: 273
273-861The horizontal rows in periodic table called periods and vertical columns in the periodic table are called groups
Question: 274
What are two factors on which evaporation depends ?
Answer: 274
274-861Surface area : Evaporation is a surface phenomenon . Greater is surface area greater is evaporation
Question: 275
Why the size of atom does not decrease regularly in periods ?
Answer: 275
275-861The atomic size does not decrease regularly in periods due to presence of transition elements . The size of atom first decreases then increases
Question: 276
Why solution is considered mixture ?
Answer: 276
276-861The 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: 277
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: 277
277-861Elements in group 3 to 12 elements are normal elements because their valence electrons lie in s and p sub shell
Question: 278
Why and how are element arranged in 4th period ?
Answer: 278
278-861Elements 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: 279
For an element Z = 92 A = 238 Calculate number of neutron in it
Answer: 279
279-861Atomic mass = No of protons + No of neutrons =A=238
No of protons Z = 92
No of neutrons =N=A-z
=238-92= 146
Question: 280
What is meant by condensation ?
Answer: 280
280-861The returns of the vapours into liquids state on cooling is called condensation
Question: 281
How atoms accommodate 8 electrons in their valence shells?
Answer: 281
281-861toms 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: 282
What are SI units of atomic radius ?
Answer: 282
282-861Pico meter (pm) =10-12m
Question: 283
How cation and anion is formed ?
Answer: 283
283-861Cation is formed by the loss of one or more electrons
Question: 284
Why shielding effect of electron makes action formation easy ?
Answer: 284
284-861As 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: 285
Define modern periodic law ?
Answer: 285
285-861In 1913 H.Moseley given Modern law
Properties of elements are periodic function of their atomic masses
Question: 286
Show the state of Dynamic equilibrium in liquid and vapours with the help of diagram .
Answer: 286
286-861From 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: 287
What are blocks ? How many blocks are present in periodic table ?
Answer: 287
287-861On 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: 288
What is vapour pressure ?
Answer: 288
288-861The pressure exerted by the vapour of a liquid at equilibrium with the liquid at a particular temperature is called vapour pressure of liquid
Question: 289
Electronic configuration of Cl- ion
Answer: 289
289-861Cl-1s2 ,2s2,2p6 ,3s2 ,3p6
Question: 290
What is relationship between Empirical formula and Molecular formula ?
Answer: 290
290-861The relationship between Empirical formula and Molecular formulais given as
Molecular formula = (Empirical formula)*n
When n = 1,2 ,3 and so on
Question: 291
Write the chemical formula of water and sugar.
Answer: 291
291-861Water :C12H22O11
Question: 292
Why does evaporation increases with the increase in temperature ?
Answer: 292
292-861Evaporation 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: 293
What is the affect of temperature on vapour pressure ?
Answer: 293
293-861By increasing temperature , vapour pressure increases and by decreasing temperature vapour pressure decreases
Question: 294
What is effective nuclear charge ?
Answer: 294
294-861The valence electron of an atom experiences less nuclear change than that of actual charge , it is called effective nuclear charge or Zeff
Question: 295
On which two factors vapour pressure of any liquid depends ?
Answer: 295
295-861Vapour pressure of liquid depends upon following factors :
Question: 296
How many elements are in 3rd period, write their names and symbols?
Answer: 296
296-861There are eight elements in 3' period, sodium(Na), magnesium(Mg) .aluminium (AI).silicon(Si),phosphorus(P),sulphur(S),chlorine(Cl),argon(Ar)
Question: 297
What type of solution fog and brass are?
Answer: 297
297-8611: Fog is a solution of liquid solute in gas solvent
Question: 298
What are the defects of Mendeleev's periodic table or why improvement was make in Mendeleev's periodic table?
Answer: 298
298-861There are two defects in Mendeleev's periodic table:
Question: 299
Why does evaporation cause cooling ?
Answer: 299
299-861When 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: 300
Write down chemical formula of calcium phosphate and sodium chloride ..
Answer: 300
300-861Chemical formula of calcium phosphate and sodium chloride is as fellows :
Question: 301
How meat can be preserved ?
Answer: 301
301-861Table 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: 302
What are Lanthanide and actinide series ?
Answer: 302
302-861Due to space problem two series of elements are placed below periodic table
Question: 303
Why do atoms react ?
Answer: 303
303-861It 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: 304
Calculate the formula mass of the sodium sulphate .
Answer: 304
304-861Formula mass of the sodium sulphate :
Na2so4 =2(23) +(32)+4(16)
=46+32+64
=142amu
Question: 305
Why solid show rapidly ?
Answer: 305
305-861The particles of solids are fixed at their position and are not mobile . Therefore they have rigid structure and definite shape .
Question: 306
Define periodicity ?
Answer: 306
306-861Properties of elements were found repeating after regular intervals in periodic table it is the periodicity
Question: 307
Convert -30°C to K unit
Answer: 307
307-861As 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: 308
Write down the names of elements of groups 1 with their symbols .
Answer: 308
308-8611st 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: 309
Why is the bond between an electropositive and an electronegative atom ionic in nature ?
Answer: 309
309-861Because 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: 310
Define melting point ?
Answer: 310
310-861The temperature at which the solid starts melting and exists in dynamic equilibrium with liquid state is called melting point
Question: 311
Why do ionic compounds conduct electricity in solution or molten form?
Answer: 311
311-861Ionic compounds are good conductor in solution and molten form due to the presence of free ions in them
Question: 312
What characteristics properties do the covalent compound have ?
Answer: 312
312-861They 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: 313
What is the empirical formula of acetic acid ? Calculate its molecular mass.
Answer: 313
313-861Empirical formula of acetic acid CH2O
Question: 314
Write down the chemical formula of silicon dioxide and calcium chloride .
Answer: 314
314-861Silicon dioxide SiO2
Question: 315
In which pattern modern periodic table was arranged?
Answer: 315
315-861According to increasing atomic number.
Question: 316
Write two properties of crystalline solids .
Answer: 316
316-8611: In crystalline solids particles are arranged in definite in definite pattern .
Question: 317
Write two difference between atom and anion
Answer: 317
317-861Ion :
1: It is the simplest unit of ionic compound
2: It has net charge either negative or positive on it
Question: 318
What type of bond exists in ionic compound?
Answer: 318
318-861Ionic bond exists in ionic compound.
Question: 319
Why atomic number is more fundamental property to arrange elements than atomic mass?
Answer: 319
319-861Due to two reasons :
1: It increase regularly from element to element
Question: 320
Define molecular mass and give example .
Answer: 320
320-861Molecular formula that shows actual number of atoms of each element present in molecules of that compound
Question: 321
Describe difference between concentrated and dilute solution .
Answer: 321
321-861Concentrated solution : The solution which contains relatively large amount of dissolved solute in solution is called concentrated solution
Question: 322
Give the trend of ionization energy in a period ?
Answer: 322
322-861If 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: 323
Define solution with example .
Answer: 323
323-861A 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: 324
What is difference between cation and anion ?
Answer: 324
324-861Cation: An atom or group of atoms having positive charge on it is called cation
Example : like Na , k
Question: 325
What do you mean by evaporation and how it is affected by surface area?
Answer: 325
325-861Evaporation: 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: 326
How the properties of elements repeat after regular intervals?
Answer: 326
326-861The 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: 327
Calculate molecular mass of NH3.
Answer: 327
327-861Molecular mass :
NH3 =14+1*3
=17a.m.u
Question: 328
How many members are in group 17, is there any liquid, what is its name?
Answer: 328
328-861There 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: 329
Describe atIeast two necessary conditions for the formation of a covalent bond.
Answer: 329
329-861Iwo 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: 330
Why dose ice float on water?
Answer: 330
330-861lCe 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: 331
Why do atoms form chemical bonds?
Answer: 331
331-861Atoms achieve stability by attaining electronic configuration of inert gases ns2 or ns2,np6 Atoms combine with one another. which is called chemical bond.
Question: 332
Write the simplest way to distinguish between solution and pure liquid .
Answer: 332
332-861The 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: 333
Why the elements are called s and p block elements?
Answer: 333
333-861The elements having their valence electrons in s and p sub shell called s and p blocks elements.
Question: 334
Define empirical formula and give an examples .
Answer: 334
334-861Empirical formula: empirical formula is a formula which represents the simplest whole number ratio of atoms present in a compound
Question: 335
What is the difference between the evaporation and boiling point ?
Answer: 335
335-861Evaporation : The process of changing of a liquid into a gas phase is called evaporation .
Question: 336
Calculate the formulas mass of potassium sulphate
Answer: 336
336-861Formulas mass of potassium sulphate (K2SO4)
K2SO4 = 2(39)+(32)+4(16)
= 78+32+64
= 174a.m.u
Question: 337
What is the reason of arranging elements in a group?
Answer: 337
337-861The reason of arranging of elements in a groups, is that they have same electronic configuration and same properties so they form a family.
Question: 338
Is sign of (0) used on Kelvin?
Answer: 338
338-861No. Degree sign (°) is used with Celsius scale not with Kelvin scale.
Question: 339
What type of covalent bond is formed in nitrogen molecule?
Answer: 339
339-861In 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: 340
Why noble gases are non-reactive?
Answer: 340
340-861The 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: 341
Write formulas of two ionic compounds which are soluble in water .
Answer: 341
341-861The two ionic compound which are soluble in water are following
Question: 342
How many elements are in first period and what are their names and symbols?
Answer: 342
342-861There are two elements in first period, hydrogen (H), helium(He)
Question: 343
If repulsive forces dominate to attractive forces will a covalent bond form?
Answer: 343
343-861If 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: 344
Define formula mass and formula unit .
Answer: 344
344-861Formula unit : formula unit is defined as the simplest whole number ratio of ions ,as present in the ionic compounds
Question: 345
Calculate the molecular mass of the carbon dioxide .
Answer: 345
345-861Molecular mass of the carbon dioxide
CO2 = 12+2 (16)
= 44amu
Question: 346
Define atomic radius ?
Answer: 346
346-861The half of the distance between the nuclei of the two bonded atoms referred as atomic radius
Question: 347
Why volume of a gas decreases with increase of pressure"
Answer: 347
347-861The 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: 348
How free radical is formed ?
Answer: 348
348-861Free radicals are formed by the homolytic (equal) breakage of bond between two atoms when they absorb heat or light energy
Question: 349
What is solid-liquid solution ? Explain with example .
Answer: 349
349-861When 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: 350
Why does sodium lose one electron and attain +1 charge?
Answer: 350
350-861Sodium 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: 351
Ionic compounds conduct electricity in solution or molten form. Why?
Answer: 351
351-861Ionic 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: 352
Calculate molecular mass of sulphuric acid .
Answer: 352
352-861Molecular mass of sulphuric acid H2SO4
=2(1)+(32)+4(16)
=98amu
Question: 353
Write chemical formula of Aluminium sulphate and Calcium phosphate .
Answer: 353
353-861Aluminium sulphate: Al2(SO4)
Question: 354
Explain the law of flow of heat ?
Answer: 354
354-861In 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: 355
What is solid-solid solution ? Give two examples .
Answer: 355
355-861Alloy: When solid solvent and solid solute make solutions it is called solid-solid solution
Question: 356
What is diffusion ? Explain with example ?
Answer: 356
356-861Diffusion is defined as spontaneous mixing up of molecules by random motion and collisions to form a homogeneous mixture
Question: 357
Calculate the formula mass of the nitric acid .
Answer: 357
357-861HNO3 = 1+14+48
= 63amu
Question: 358
Define transition element ?
Answer: 358
358-861d block elements called transition element
Question: 359
Write the names of two allotropic forms of sulphur .
Answer: 359
359-861The allotropic forms of sulphur are given below :
Question: 360
What do you mean by induced dipole?
Answer: 360
360-861The charges in one molecule creates charges in other molecules these charges are called induced dipole.
Question: 361
Write two difference between molecule and molecular ions .
Answer: 361
361-861Molecule :
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: 362
Define allotropy and give examples .
Answer: 362
362-861The existence of an element in more than one form in same physical state but different chemical properties is called allotropy .
Question: 363
What do you mean by %volume/volume
Answer: 363
363-861It 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: 364
What is absolute temperature scale?
Answer: 364
364-861Lord 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: 365
What do you mean by malleability?
Answer: 365
365-861Malleability is the property by virtue of which metals can be drawn into sheets.
Question: 366
Define aqueous solution . Write its components .
Answer: 366
366-861The 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: 367
What is meant by ion ? Give example .
Answer: 367
367-861Ion is an atom or group of atoms having a charge on it .
Question: 368
Differentiate between crystalline and amorphous solid .
Answer: 368
368-861Crystalline solid : Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solid
Question: 369
Why is 02 necessary for rusting?
Answer: 369
369-86102 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: 370
What is difference between polar and non-polar covalent bonds, explain with one example of each?
Answer: 370
370-861Polar 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: 371
What is a triple covalent bond, explain with an example?
Answer: 371
371-861Ans: 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: 372
Write the name of two non-polar solvents .
Answer: 372
372-861Toluene and benzene aretwo non-polar solvents
Question: 373
Why are dipole forces of attraction not found in halogen molecules?
Answer: 373
373-861Dipole forces of attraction do not found in halogen molecules because they have same electronegativity and there is equal sharing of electrons.
Question: 374
Anode of downs cell is made up of non metal , what is its name ?
Answer: 374
374-861Anode of down cell is made of non-metal , Its name is graphite . The Cl- ions are oxidized to give Cl2 gas at anode
Question: 375
Convert the following. Ans: a) 70 cm lig to atm. b) 3.50atm to torr. c) 1.5 atm to Pa.
Answer: 375
375-86170 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: 376
Differentiate between lone pair and bond pair of electron.
Answer: 376
376-861Lone 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: 377
What is difference between solution and mixture ?
Answer: 377
377-861Solution : Homogenous mixture of two or more substance called solution
Question: 378
Write difference between homoatomic and heteroatomic molecules ?
Answer: 378
378-861Heteroatomic molecules:
The molecules consisting of different types of atoms are called heteroatomic molecules
Question: 379
Which allotropic form of carbon is stable at room temperature (25°C)?
Answer: 379
379-861Graphite is more stable at room temperature
Question: 380
Why the ionic compounds have high melting and boiling points?
Answer: 380
380-861Ionic 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: 381
Define transition temperature . Give example .
Answer: 381
381-861The temperature at which one allotropes changes into another is called is called transition temperature
Question: 382
Calculate the number of mole carbon in 84 gram of carbon .
Answer: 382
382-861 Mass of C = 84 gm
Molecular mass of C = 12 gm
Quantity of moles = 84/12
= 7 moles
Question: 383
Differentiate bonding electrons and non-bonding electrons•
Answer: 383
383-861The 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: 384
Define Crystalline solids and give two examples .
Answer: 384
384-861Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids
Question: 385
Define standard atmospheric pressure . What are its units ? How it is relate to the pascal ?
Answer: 385
385-861It is defined as the pressure exerted by a mercury column of 760 mm height at sea level
Question: 386
Define unsaturated solution .
Answer: 386
386-861The solution which have capacity to dissolve more amount of solute is called unsaturated solution
Question: 387
How does nature of attractive forces of solute-solute solvent -solvent affect the solubility?
Answer: 387
387-861Solutions 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: 388
Write properties of Neutrons .
Answer: 388
388-861Properties of neutrons particles are given below :
Question: 389
Write difference between saturated solution and unsaturated solution .
Answer: 389
389-861Saturated solution : The solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 390
Differentiate duplet and octet rule.
Answer: 390
390-861Duplet Rule:
Attaining two electrons in valence called duplet rule.
Example. , Li+Hefollow duplet rule.
Question: 391
What is difference between solution aqueous solution ?
Answer: 391
391-861Solution : A solution is a homogenous mixture of two or more substance
Question: 392
Name the by-products produced in Nelson's Cell?
Answer: 392
392-861The chlorine and hydrogen gas are produce as by product in Nelson's Cell
Question: 393
Give two examples of gas in liquid solution .
Answer: 393
393-8611: Fog
Question: 394
Write down the number and names of subshell in N-shell .
Answer: 394
394-861Number of sub shell in N shell is 4 named as s ,p ,d and f
Question: 395
Why HCl has dipole-dipole forces of attraction?
Answer: 395
395-861HCl 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: 396
How do atoms follow octet rule?
Answer: 396
396-861Atoms 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: 397
What type of solutions butter and smoke are ?
Answer: 397
397-861Solution : Butter , smoke
Question: 398
Why arc the densities of gases tower than that of liquids?
Answer: 398
398-861Gases has e low density than liquids and solids. It is due to light mass and more volume occupied by the gas molecules.
Question: 399
Write electronic configuration of Sulphur .
Answer: 399
399-861Electronic configuration of Sulphur :
Question: 400
Give the characteristics properties of ionic compounds
Answer: 400
400-861the 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: 401
Difference between oxidation state and valency
Answer: 401
401-861Oxidation : 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: 402
Does Kelvin scale show negative temperature?
Answer: 402
402-861No. Kelvin scale does not show a negative temperature
Question: 403
What is difference between solute and solvent ?
Answer: 403
403-861Solute : The component of the solution which is present in smaller quantity is called solute
Question: 404
Why is BF3, electron deficient?
Answer: 404
404-861In 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: 405
Define solubility ?
Answer: 405
405-861The amount of solute in grams dissolved in 100g of solvent to prepare saturated solution at a particular temperature is called solubility of solute .
Question: 406
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: 406
406-861Electronic 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: 407
How many atoms of hydrogen present in one mole of water ?
Answer: 407
407-861One 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: 408
Define super-saturated solution .
Answer: 408
408-861The solution that is more concentrated than a saturated solution at a given temperature is known as super- saturated solution
Question: 409
What is ionic bond? Give an example.
Answer: 409
409-861Definition: A chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond.
Question: 410
Differentiate between gram atomic mass and gram molecular mass .
Answer: 410
410-861Gram atomic mass: The atomic mass of an element expressed in grams . It is called gram atomic mass
Question: 411
Why big size covalent molecules have high melting and boiling points?
Answer: 411
411-861Bigger molecules with three dimensional bonding form covalent crystals which are very stable and have high melting and boiling points.
Question: 412
Write down uses of radioactive isotopes as traces for diagnosis and medicine .
Answer: 412
412-8611: The radioactive isotopes are used as tracer to diagnose the presence of tumor inside the body
Question: 413
Define Triatomic molecule and polyatomic molecule
Answer: 413
413-861Polyatomic molecule : The molecules which consists of many atoms calledpolyatomic molecule
Question: 414
Why ionic compounds easily dissolve in water?
Answer: 414
414-861They dissolve easily in water because water is a polar solvent and has high dielectric constant that weakens the attraction between ions.
Question: 415
What are cathode rays ? Who discovered it?
Answer: 415
415-861In 1897 JJ Thomson discovered cathode rays
Question: 416
Why is the hold of nucleus over the outermost electrons in metal weak ?
Answer: 416
416-861The 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: 417
Write two examples of gas into gas solution .
Answer: 417
417-8611:Air
Question: 418
Can, you cool a gas by increasing its volume
Answer: 418
418-861No. we cannot cool a gas by increasing its volume
Question: 419
Define molarity and write its equation .
Answer: 419
419-861It is a concentration unit defined as number of moles of solute dissolved in one dm3 of solution . It is represented by M.
Question: 420
Write down the position of hydrogen in the periodic table
Answer: 420
420-861First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 421
What will happen if the pressure temperature is kept constant?
Answer: 421
421-861The volume of gas will decrease three times when its pressure raised up to three times as temperature.
Question: 422
Calculate the value of angular momentum of 1st orbit where mvr = nh/2π
Answer: 422
422-861Let angular momentum (mvr) of first orbit is =mvr = nh/2π
Question: 423
What type of elements have tendency of sharing of electrons?
Answer: 423
423-861If 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: 424
How many normal periods are and name also?
Answer: 424
424-8612nd and 3rd periods are known as normal periods and they are two in number
Question: 425
State whether allotropy is shown by elements or compounds or both ?
Answer: 425
425-861Allotropy is only shown by elements . It is not a property of compounds
Question: 426
What is difference between ion and free radical ?
Answer: 426
426-861Free 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: 427
What type of elements form metallic bond?
Answer: 427
427-861Metals form metallic bond
Question: 428
How many sub shell are there in second sub shell ?
Answer: 428
428-861In second sub shell 'L ' has two sub shells s and p
Question: 429
how can you explain the solute-solvent interaction to prepare NaCI Solution?
Answer: 429
429-861When 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: 430
Why chlorine can accept only 1 electron?
Answer: 430
430-861Chlorine 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: 431
What do you mean by delta sign and why it develop ?
Answer: 431
431-861The 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: 432
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: 432
432-861Using the relationship :
Question: 433
Write down the trend of atomic size in the periodic table.
Answer: 433
433-861In period : Atomic size in a period from left to right decreases
Question: 434
What types of electron pairs make a molecule good donor ?
Answer: 434
434-861The lone pair of electron make a molecule a good donor
Question: 435
How much NaOH is required to prepare its 500cm3 of 0.4m solution?
Answer: 435
435-861Molar mass of NaOH =40gmol-3
Question: 436
Why is galvanizing done?
Answer: 436
436-861The 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: 437
Why does group 1 elements prefer to combine with group 17 elements.
Answer: 437
437-861The 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: 438
Why ionization energy decreases in a group from top to bottom ?
Answer: 438
438-861When 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: 439
Which variables are kept constant in Charles' law?
Answer: 439
439-861Pressure is kept constant in Charles' law
Question: 440
An element X has oxidation state 0 . What will be the oxidation state when it gains three electrons ?
Answer: 440
440-861Suppose the element x
X0 +3e-➜ X-3
Question: 441
Why is the formula of solute necessary for calculation of the molarity of the solution ?
Answer: 441
441-861Formula of solute is necessary for calculation of the molarity of the solution because molarity depends upon No. of moles of solute
Question: 442
Write two uses of isotopes
Answer: 442
442-8611: In the field of medicine isotopes of iodine 131 are use for diagnose of goiter in thyroid gland
Question: 443
In which units body temperature is measured ?
Answer: 443
443-861Body 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: 444
Which is the simplest form of matter?
Answer: 444
444-861Gas is the simplest form of matter.
Question: 445
Define m0ole and give example .
Answer: 445
445-861Atomic mass , molecular mass or formula mass of a substance expressed in grams is called a mole
Question: 446
Give two characteristics of colloid .
Answer: 446
446-8611: Colloid particles are large but can't be seen with naked eyes
Question: 447
Give the electronic configuration of carbon atom.
Answer: 447
447-861Atomic no. of carbon = Z= 6
No of electrons in carbon atom =Z=6
Electronic configuration of carbon atom=ls2.2s2,2p2
Question: 448
Define diatomic molecule and give example .
Answer: 448
448-861If a molecule consists of two atoms called diatomic molecule
Question: 449
Describe two characteristics of canal rays .
Answer: 449
449-8611: 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: 450
Justify with an example the solubility of salt increases with increase in temperature?
Answer: 450
450-861When 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: 451
How a covalent bond becomes polar?
Answer: 451
451-861When 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: 452
What is periodic law?
Answer: 452
452-861In 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: 453
In which form sulphur exists at I00°C?
Answer: 453
453-861Sulphur 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: 454
Define electronic configuration . Also give example .
Answer: 454
454-861The distribution of electrons around the nucleus in various shells and sub shells according to their increasing energy is called electronic configuration.
Question: 455
What is the sign of stability of an atom ?
Answer: 455
455-861The 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: 456
Why an iron grill is painted frequently?
Answer: 456
456-861Iron 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: 457
Define the term allotropy ?
Answer: 457
457-861Allotropy: The existence of an element in more than one forms in same physical state is called allotropy.
Question: 458
Which are long periods ? How many elements are present in long periods ?
Answer: 458
458-8614th 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: 459
How can you justify that blood is a colloid?
Answer: 459
459-861Blood 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: 460
Which type of electron are responsible for holding the atoms together in metals ?
Answer: 460
460-861Nuclei 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: 461
An element in oxidation state +7 gains electrons to be reduced to oxidation state +2 . How
Answer: 461
461-861Suppose an element X +7
Question: 462
What type of attractive forces exist between HCL molecules ?
Answer: 462
462-861Dipole-dipole attractiveforces exist between HCL molecules.
Question: 463
Write down atomic number of nitrogen and oxygen .
Answer: 463
463-861The atomic no of N2 is = 7
Question: 464
Which form of Sulphur exists at room temperature?
Answer: 464
464-861Rhombic (S8) Sulphur exists at room temperature
Question: 465
Define oxidation in terms of oxygen with an example .
Answer: 465
465-861Oxidation : The addition of oxygen in any chemical reaction is called oxidation reaction
Question: 466
Why does a dipole develop in a molecule ?
Answer: 466
466-861The 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: 467
If 16g of oxygen contains 1 mole of oxygen atom, calculate the mass of one atom of oxygen in grams .
Answer: 467
467-861No of atoms in one mole =6.02×1023
Question: 468
Write down names of elements of first group and second period of the periodic table .
Answer: 468
468-861First group of periodic table consists of hydrogen , lithium , sodium , potassium , rubidium , cesium , francium
Question: 469
Why has water polar covalent bond ?
Answer: 469
469-861Water 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: 470
What is the reason of deficiency of electrons in BF3?
Answer: 470
470-861In 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: 471
Why are the liquids mobile.
Answer: 471
471-861Liquid 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: 472
How much amount of KOH required to form 1 molar solution ?
Answer: 472
472-861Concentration of solution = 1dm3
Molar mass of KOH = 39+16+1
= 56 mol
Question: 473
Which electrons are involved in chemical bonding?
Answer: 473
473-861Only valence shell electrons are involved in chemical bonding
Question: 474
Write short note on discovery of Neutron.
Answer: 474
474-861Chadwick 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: 475
Whether the density of a gas decreases on cooling ?
Answer: 475
475-861The density of gas increase by cooling because their volume decreases
Question: 476
What is meant by metallic bond ?
Answer: 476
476-861When positively charged metal ions are held together by freely moving electrons , the bond which is formed called metallic bond
Question: 477
Why gases are compressible ?
Answer: 477
477-861Gases 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: 478
What is the trend of ionization energy in the group ?
Answer: 478
478-861As 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: 479
How will you test whenever given solution is colloidal solution or not?
Answer: 479
479-861If 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: 480
Define electrolytes and electro chemical cell .
Answer: 480
480-861Electrolytes : The substances , which can conduct electricity in their aqueous solution or molten state , are called electrolytes
Question: 481
State Charles's law
Answer: 481
481-861The volume of a given mass of a gas is directly proportional to the absolute temperature when pressure kept constant."
Question: 482
Why are the rates of diffusion in liquids slower than that of gases?
Answer: 482
482-861In 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: 483
Is the Boyle's law valid at very high temperature?
Answer: 483
483-861No. Boyle's law is not valid at very high temperature
Question: 484
What is absolute zero?
Answer: 484
484-861It is the temperature at which an ideal gas would have zero volume.
Question: 485
Describe exothermic reaction with example .
Answer: 485
485-861Exothermic 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: 486
An element has 5 electrons in M shell . Find its atomic number
Answer: 486
486-861The element has 5 electrons in M shell has atomic number 15 and name of element is phosphorous
Question: 487
Differentiate saturated and unsaturated solution
Answer: 487
487-861Saturated : A solution containing maximum amount of solute at a given temperature is called saturated solution
Question: 488
What is the trend of variation in densities of alkali metals?
Answer: 488
488-861Densities of alkali metals increases down the group in the periodic table
Question: 489
What is the relationship between evaporation and boiling point of a liquid?
Answer: 489
489-861Boiling 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: 490
What is the reason for the difference between solutions, colloids and suspensions?
Answer: 490
490-861Particles 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: 491
Which isotopes are called radioactive isotopes ?
Answer: 491
491-861The isotopes have ability to emit radiation naturally called radioactive isotopes
Question: 492
What do you mean by 24 carat gold ?
Answer: 492
492-861Purity 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: 493
Why atoms form bond ?
Answer: 493
493-861It 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: 494
What is the nature of electrode used in electroplating of chromium?
Answer: 494
494-861The object to be electroplated acts as cathode while anode is made of antimonial-lead.
Question: 495
Why the electrons move freely in metals ?
Answer: 495
495-861This 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: 496
Write electronic configuration of Aluminuim .
Answer: 496
496-861Atomic number of Aluminium is 13
13Al = 1s2 , 2s2, 2p6, 3s2, 3p1
Question: 497
What is difference between Mendeleev's periodic law and modern periodic law?
Answer: 497
497-861Mendeleev's periodic law : The properties of elements are the periodic function of atomic masses
Question: 498
Define aqueous solution
Answer: 498
498-861The solution which is formed by dissolving a substance in water is called an aqueous solution
Question: 499
What is tyndall effect ? On which factor it depends ?
Answer: 499
499-861Tydnall effect: The particles of colloids are big enough to scatter the beam of light . It is called tydnall effect
Question: 500
When a gas is allowed to expand, what will be its effect on its temperature?
Answer: 500
500-861According to Charles' Law when gas is allowed to expand its temperature also increases.
Question: 501
What is transition temperature of sulphur?
Answer: 501
501-861Its transition temperature is 96℃.
Question: 502
Define molar solution and give example .
Answer: 502
502-861When one mole of solute is solved on one dm3 of solvent in measuring flask then it is called one molar solution
Question: 503
Who discovered proton and neutron ?
Answer: 503
503-861Proton is discovered by Goldstein in 1886
Question: 504
Write the redox reaction taking place during the electroplating of chromium.
Answer: 504
504-861Reaction at the electrodes are as Follows:
At anode 40H-➜2H2O+O2+4e-
At cathode C+33e-➜Cr
Question: 505
Why the elements of group 13 to group 18 are called P block elements ?
Answer: 505
505-861Elements of group 13 to 18 have their valence electrons in P subshell . Therefore , they are called as P-block elements
Question: 506
Why does evaporation increase with the increase of temperature?
Answer: 506
506-861At 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: 507
Why is vapour pressure higher at high temperature?
Answer: 507
507-861At 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: 508
Why is melting point of a solid considered its 'identification' characteristics ?
Answer: 508
508-861The 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: 509
Define reduction .
Answer: 509
509-861Reduction is defined as addition of hydrogen or removal of oxygen during a chemical reaction
Question: 510
Why the density of a gas is measured in gdm-3while that of a liquid is expressed in gcm-3?
Answer: 510
510-861The 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: 511
Why suspensions and solutions do not show Tyndall effect , while colloids do ?
Answer: 511
511-861Suspensions 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: 512
Why amorphous solids do not have sharp melting points while crystalline solids do have ?
Answer: 512
512-861Amorphous 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: 513
What are two defects in Rutherford's atomic model ?
Answer: 513
513-8611: 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: 514
Molecular formula of a sulphur molecule
Answer: 514
514-861The Molecular formula of a sulphur molecule S8
Question: 515
Which force drives the non-spontaneous reaction to take place ?
Answer: 515
515-861Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
Question: 516
Why the rate of diffusion of gases is rapid than that of liquid ?
Answer: 516
516-861The 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: 517
Why does rate of diffusion increase with increase of temperature?
Answer: 517
517-861Diffusion increases by increasing temperature because at high temperature the in termolecular forces become weak due to high kinetic energy of the molecules
Question: 518
Calculate the gram molecule in 40g of phosphoric acid
Answer: 518
518-861Molar mass of phosphoric acid H3PO4 = 3+31+64=98
Question: 519
Write example of use of radioactive isotopes in the field of medicine and radiotherapy
Answer: 519
519-861In 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: 520
State any four physical properties of metals.
Answer: 520
520-861Physical 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: 521
Why we stir paint thoroughly before using?
Answer: 521
521-861We 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: 522
What is meant by atomic radius ? What is its unit ?
Answer: 522
522-861The half of the distance between the nuclei of two of similar adjacent (bonded) atoms is called atomic radius
Question: 523
Describe at least two necessary conditions for the formation of covalent bond .
Answer: 523
523-8611: A covalent bond is formed between two non-metals
Question: 524
Define solution ?
Answer: 524
524-861A solution is homogenous mixture of two or more substances
Question: 525
Write down the electronic configuration of following
1: Na 2: Al
Answer: 525
525-8611: Atomic number of Na 11
11Na = 1s2. 2s2 . 2p6 . 3s1
Question: 526
What do you mean like dissolve like ? Explain with example ?
Answer: 526
526-861The 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: 527
Write down the name of particles which determine the mass of an electron .
Answer: 527
527-861The proton and neutron determine the mass of an atom
Question: 528
Give example of two polar compounds and give their chemical formula .
Answer: 528
528-861Following are some examples of two polar compounds :
Question: 529
Which is lighter one aluminium or gold?
Answer: 529
529-861Aluminum is lighter than gold because density or aluminium is 2.70 gcm'-3 While of gold is 9.3 gcm-3
Question: 530
How is the periodicity of properties depends upon the number of proton in an atom ?
Answer: 530
530-861Periodicity 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: 531
Which of the following will scatter light and why?
Sugar solution, Soap solution, Milk of magnesia.
Answer: 531
531-861Soap solution is colloidal solution and have particles large enough to scatter the light
Question: 532
Define redox reaction , Give an example .
Answer: 532
532-861The reaction in which oxidation as well as reduction takes place at a time called redox reaction
Question: 533
Why the 2nd ionization energy is greater than 1st ionization energy ?
Answer: 533
533-861Because 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: 534
Why suspension does not form homogeneous mixture?
Answer: 534
534-861sn, Particles remain un dissolved and from a heterogeneous mixture. Particles settle down after some times.
Question: 535
Write down electronic configuration of sodium .
Answer: 535
535-861Electronic configuration of sodium
11Na = 1s2 , 2s2 , 2p6 , 3s1
Question: 536
How sodium metal is obtained from fused sodium chloride .
Answer: 536
536-861On 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: 537
Why ionization energies of alkaline earth metals are higher than alkali metals?
Answer: 537
537-861Alkaline 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: 538
What is the percentage m/volume ?
Answer: 538
538-861It is the number of grams of solute dissolved in 100cm3of solution
Question: 539
Why benzene is insoluble in water ?
Answer: 539
539-861The 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: 540
Why elements of group 1 and group 2 are called S block elements?
Answer: 540
540-861There are four blocks in the periodic table named after the name of the subshell which is in the process of completion by electrons .
Question: 541
What is meant by true solution ?
Answer: 541
541-861True 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: 542
Name a metal which can be cut with knife?
Answer: 542
542-861Sodium is that metal which can be cut with knife, because it is soft.
Question: 543
In electroplating of chromium which salts is used as an electrolyte?
Answer: 543
543-861In electroplating of chromium, Cr2(SO4)3, is used as an electrolyte.
Question: 544
Why do electrodes get their names "anode" and cathode in galvanic cell?
Answer: 544
544-861In galvanic, cell. Oxidation take place at anode while reduction take place at cathode
Question: 545
What is maximum capacity of a metal ?
Answer: 545
545-8611: K shall can accommodate 2 electrons
Question: 546
Can colloids he separated by filtration, if not why?
Answer: 546
546-861Colloids cannot be separated by filtration because particles are big but they can pass through a filter paper.
Question: 547
What are anode or cathode ?
Answer: 547
547-861Anode : It is the electrode at which the oxidation takes place
Question: 548
Differentiate between solute and solvent ?
Answer: 548
548-861Solute : The component which is present in smaller quantity is called solutee.g : Salt in water , salt is solute
Question: 549
Why does atomic size increases in a group ?
Answer: 549
549-861The 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: 550
What would be the number of moles in 9.0 gram carbon ?
Answer: 550
550-861Number of moles of carbon = 9 g
Molar mass of carbon = 12 g
Number of moles = ?
Question: 551
Name the most abundant non- metal in earth's crust?
Answer: 551
551-861Oxygen has has the highest percentage in earth's crust 47% and oceans 86% but second highest percentage in atmosphere 21%
Question: 552
Why is white tin available at room temperature?
Answer: 552
552-861White tin available at room temperature because it is stable at room temperature above 13.2°C
Question: 553
For what purpose P-32 and Sr - 90 are used .
Answer: 553
553-8611: For the treatment of skin cancer , isotopes like P-32 and Sr-90 are used because they emit less penetrating beta radiations
Question: 554
Differentiate between oxidation and reduction.
Answer: 554
554-861Oxidation : Oxidation is defined as addition of oxygen or removal of hydrogen during a chemical reaction
e.g
ZnO + C➜Zn +CO2
Question: 555
What is the half cell reactions occuring on cathode and anode in Daniel cell ?
Answer: 555
555-861Following reactions occur at cathode and anode in Daniel cell .
Question: 556
What is meant by octet rule ?
Answer: 556
556-861Attaining 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: 557
Write two method for prevention of corrosion .
Answer: 557
557-861Method for prevention of corrosion:
Following are some method from avoiding corrosion
Question: 558
What happens to iron in the rusting process ?
Answer: 558
558-861The oxidation of iron take place during rusting process and forms Fe2O3 . The chemical formula of rust is Fe2O3nH2O
Question: 559
Define oxidation state ?
Answer: 559
559-861Oxidation state is the apparent charge assigned to an atom of an element in a molecule or ion
Question: 560
Why does true solutions not show Tyndall effects?
Answer: 560
560-861True 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: 561
Write down electronic configuration of phosphorous .
Answer: 561
561-861Atomic number of phosphorous is 15 Electronic configuration is given as below :
Question: 562
Define avagadro's number
Answer: 562
562-861Avagadro'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: 563
What is redox reaction ?
Answer: 563
563-861The reaction in which simultaneously oxidation and reduction takes place is called redox reaction
Question: 564
Define oxidation and give example .
Answer: 564
564-861Oxidation reaction : The loss of electron by an atom or ion is called oxidation .
Question: 565
What is general principle of solubility ?
Answer: 565
565-861The 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: 566
How does electron differ from a neutron ?
Answer: 566
566-861Electron
1: Electrons have negative charge
2: The mass of the electron is 1940 times less than proton
Question: 567
In electroplating of silver, from where Ag+ ions come and where they deposit?
Answer: 567
567-861In 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: 568
Classify the following into true solution and colloidal solution?
Answer: 568
568-861Blood, 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: 569
Why ionization energy of Na is less than Mg ?
Answer: 569
569-861Ionization energy of Na is less than Mg because Mg has greater nuclear charge than Na and also have smaller size
Question: 570
How electroplating of zinc is carried out ?
Answer: 570
570-861The 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: 571
What is the nature of electrode used in electroplating chromium ?
Answer: 571
571-861During electroplating chromium the object to be electroplated act as cathode with anode is made up of antiamonial lead
Question: 572
What is percentage-mass/mass(%m/m)?
Answer: 572
572-861It is the number of grams of solute in 100 grams of solution
Question: 573
What is meant by colloid ?
Answer: 573
573-861The 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: 574
How many blocks are present in periodic table ?
Answer: 574
574-861There are4 presentin periodic table called s, p, d and f block
Question: 575
Write down four important chemical properties of metals .
Answer: 575
575-8611: Metals easily lose electron and form positive ions
Na➜ Na +1 +le-
Question: 576
Write any two uses of sodium .
Answer: 576
576-8611:Sodium potassium alloy is used as a coolant in nuclear reactor
Question: 577
State John Dalton's atomic theory .
Answer: 577
577-861Main points of John Dalton's atomic theory are given as follows
Question: 578
Define Electrochemistry.?
Answer: 578
578-861Electrochemistry is the branch of chemistry which deals with the relationship b-cl electricity and chemical reactions.
Question: 579
Write two / four characteristics of cathode rays.
Answer: 579
579-8611: Cathode rays travel perpendicular to the cathode surface
Question: 580
Differentiate between shell and sub shell and give example .
Answer: 580
580-861Sub 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: 581
How is platinum used as a catalyst in automobiles and what are advantages of this use?
Answer: 581
581-861An 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: 582
What do you mean by horticulture and how it is related agriculture ?
Answer: 582
582-861It 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: 583
Define the coordinate covalent bond? Explain with one example .
Answer: 583
583-861Coordinate 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: 584
Write two properties of non-polar covalent compounds .
Answer: 584
584-8611: They do not undergo charge separation
Question: 585
What is the nature of charge on cathode ray ?
Answer: 585
585-861Cathode rays are deflected toward positive plate in an electric field showing that they are negatively charged
Question: 586
Define carbondating .
Answer: 586
586-8611: 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: 587
Write two uses of redox reaction .
Answer: 587
587-861Redox reaction are useful in batteries to produce energy and this electricity is used to drive non-spontaneous reaction
Question: 588
Describe the number of molecules in 9 g water.
Answer: 588
588-861Volume of water = 9g
Question: 589
Why silver and gold are least reactive?
Answer: 589
589-861Silver 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: 590
What is difference between Duplet rule and octet rule ?
Answer: 590
590-861Duplet rule : Attaining two electrons in the valence shell is called duplet rule
Question: 591
Why metallic character decrease along a period and increase in a group?
Answer: 591
591-861Along 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: 592
Why do the colloids show tydnall effect ?
Answer: 592
592-861Colloids shows tyndall effect because the particles of
” colloids scatter the path of light rays due to large size.
Question: 593
Why Lanthanides an Actanides are placed separately below periodic table . Explain
Answer: 593
593-861Because 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: 594
What do you know about the construction of an electrolytic cell?
Answer: 594
594-861An 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: 595
Define oxidation in terms of electrons and give an example .
Answer: 595
595-861Oxidation : The loss of electron by an atom or ion is called oxidation
Question: 596
Describe difference between Rutherford's theory and Bohr's atomic theory .
Answer: 596
596-861Rutherford'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: 597
Which compounds of halogens are stable ?
Answer: 597
597-861Halogens form very stable compounds with alkali metals
Question: 598
What is meant quantum ?
Answer: 598
598-861Quantum 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: 599
What is by-products are produced in Down's cell?
Answer: 599
599-861Chlorine is produce in the downs cell as a by product
Question: 600
What is a plum pudding theory ?
Answer: 600
600-861Thomson 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: 601
Write electronic configuration of Chloride ion Cl-
Answer: 601
601-861Electronic configuration of Chloride ion
Question: 602
Why does Aluminium not rust ? Explain
Answer: 602
602-861Aluminium 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: 603
Write down names of two very reactive metals .
Answer: 603
603-8611: Li (Lithium)
Question: 604
Metals are good conductors of electricity .Why ?
Answer: 604
604-861Metals have free moving electrons called mobile electrons . Due to presence of these electrons metals are good conductors of electricity
Question: 605
In electroplating of silver , from which electrolyte Ag+ come or where they deposit ?
Answer: 605
605-861In the electrolyte of silver (Ag+) comes from anode and deposit on cathode
Question: 606
Why water is called universal solvent ?
Answer: 606
606-861Water is called universal solvent because it dissolves almost all the solute particles present in the world
Question: 607
Write down the two postulates of Bohr's atomic model .
Answer: 607
607-8611: The hydrogen atom consists of a tiny nucleus and electrons are revolving in one of circular orbits of radius ' r ' around the nucleus
Question: 608
State the physical properties of sodium .
Answer: 608
608-8611: Its melting point is 97°C
Question: 609
What is meant by periodic function ?
Answer: 609
609-861Repetition of properties due to increases of atomic number after regular intervals in the periodic table is called periodic function
Question: 610
Why the second ionization energy of magnesium is higher than the first one?
Answer: 610
610-861he 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: 611
Wrote the observations made by Rutherford .
Answer: 611
611-861Observations made by Rutherford are as follows :
Question: 612
Describe trend of shielding effect in periodic table .
Answer: 612
612-861The 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: 613
Write down names of any two moderate reactive metals
Answer: 613
613-8611: Magnesium
Question: 614
Differentiate between Lone pair and bond pair of electrons .
Answer: 614
614-861Long pair : The pair of electrons which remain unshared during covalent bond formation is called long pair
Question: 615
Why covalent bond in H2 is non-polar ?
Answer: 615
615-861In 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: 616
Write electronic configuration of Mg
Answer: 616
616-861Atomic number of Mg 12
Question: 617
Define electrochemical cell . With the names of its types .
Answer: 617
617-861Electrochemical 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: 618
Write electronic configuration of chlorine and carbon
Answer: 618
618-861Electronic configuration of carbon : 12 C 6 = 1s2 , 2s2 , 2p2
Question: 619
Can pure gold be used for making ornaments?If not why?
Answer: 619
619-861No. 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: 620
How molar solution is prepared ?
Answer: 620
620-861One 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: 621
Where does most of the mass of an atom exists ?
Answer: 621
621-861Most 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: 622
Why silver is not used in pure form ?
Answer: 622
622-861Silver is a very soft metal that's why it is not used as such in pure
Question: 623
Why is 2nd ionization energy of magnesium very high than its 1st ionization energy
Answer: 623
623-861Second 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: 624
Write electronic configuration of Neon and Berylium
Answer: 624
624-861Atomic number of Neon 10
Question: 625
For what purpose is U-235 used ?
Answer: 625
625-861The 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: 626
Define electrolysis and give example .
Answer: 626
626-861The decomposition of compound by passing electric current through molton or aqueous solution of the compound called electrolysis
Question: 627
Write down melting point and boiling point of sodium metal .
Answer: 627
627-861Melting and boiling point of sodium metal are as follows
Question: 628
Why is the ionization energy of Na more than 'K'?
Answer: 628
628-861The 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: 629
Name the element of 1st period of periodic table
Answer: 629
629-8611st period consists only two elements hydrogen (H2|) and Helium ( He)
Question: 630
How can we distinguish a metal from non-metal by a simple physical method ?
Answer: 630
630-861Metals : On heating metals usually become soft and flexible
They are difficult to cut
Question: 631
What is difference between electron affinity and electron -negativity ?
Answer: 631
631-861Electron affinity : Energy emitted due to the absorption of an electron in gaseous atom of an element is called electron affinity .
Question: 632
Where sodium metal is obtained from fused sodium chloride .
Answer: 632
632-861Sodium metal accumulates at iron cathode in down's cell
Question: 633
Why are the colloids quite stable ?
Answer: 633
633-861In 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: 634
Write down use of paints and greases .
Answer: 634
634-8611: Greasing or painting of the surface can prevent the corrosion of iron
Question: 635
How many electrons will be in M shell of an atom having atomic no 15?
Answer: 635
635-861Atomic number 15
K shall = 2 electrons
L shall = 8 electrons
M shall = 5 electrons
Question: 636
How mass number of same elements are different ?
Answer: 636
636-861Isotopes 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: 637
Which salt is used as electrolyte in chromium electroplating ?
Answer: 637
637-861In electroplating of chromium Sulphate Cr2(SO4)3 is used an electrolyte
Question: 638
Explain the effect of temperature on solubility .
Answer: 638
638-8611: Temperature has major affect on the solubility of most of the substances
Question: 639
For what purpose C-14 is used ?
Answer: 639
639-861Uses of C-14
Question: 640
Write two physical properties of sodium hydroxide .
Answer: 640
640-8611: NaOH is crystalline solid at room temperature
Question: 641
Write electronic configuration of Boron .
Answer: 641
641-861Atomic no of Boron 5
Question: 642
Define biotechnology?
Answer: 642
642-861It deals practical of living organism to make substances for the welfare of mankind
Question: 643
What is electropositivity ? Explain with example
Answer: 643
643-861Electropositivity : 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: 644
Describe the chemical reaction of alkaline earth metals with hydrogen .
Answer: 644
644-861Alkaline 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: 645
Why the second ionization energy of magnesium is higher than than first ?
Answer: 645
645-861Second 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: 646
What is the colour of flame when sodium and calcium burn in air ?
Answer: 646
646-8611: Sodium burns in air and produce golden yellow flame
Question: 647
How many neutrons are there in C-12 , C-13 ?
Answer: 647
647-8611: C-12 has 06 neutrons
2: C-13 has 07 neutrons
Question: 648
Write down the position of hydrogen in the periodic table
Answer: 648
648-861First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period
Question: 649
What are metalloids ? Give two examples .
Answer: 649
649-861The elements whose properties are intermediate between metals and non-metals are called metalloids
Question: 650
Describe endothermic reaction with example .
Answer: 650
650-861Endothermic reactions are those reactions in which heat is absorbed in theses reactions test tubes becomes cold
Question: 651
Define Shielding effect.
Answer: 651
651-861The 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: 652
Why is calcium more electropositive than magnesium ?
Answer: 652
652-861Calcium is more electropositive than magnesium due to its large atomic size and less amount of ionization energy
Question: 653
Why does sodium form a chemical bond with chlorine ?
Answer: 653
653-861Sodium 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: 654
Why suspension and solutions do not show Tyndnall effect , while colloids do?
Answer: 654
654-861Solution 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: 655
Write down the electronic configuration of fluorine and Neon
Answer: 655
655-861Electronic configuration of fluorine:
9F=1s2 , 2s2 , 2p4
Question: 656
Define Mendeleev's periodic law .
Answer: 656
656-861Mendeleev 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: 657
What is meant by ' Like dissolves like'
Answer: 657
657-8611: 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: 658
Define triads and law of octaves .
Answer: 658
658-861Triads : The group of three elements called triads . In these groups central and middle element had atomic mass average of the other two element
Question: 659
What is atomic number of Sulphur ? Write down its electronic configuration .
Answer: 659
659-861Atomic number of Sulphur IS 16 .
Question: 660
How are elements are arranged in 4th period ?
Answer: 660
660-861In fourth period 18 elements are arranged in the ascending order of their atomic number
Question: 661
Define Newland octaves law ?
Answer: 661
661-861In 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: 662
Write down two uses of gold .
Answer: 662
662-861Because 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: 663
Can pure gold be used for making ornaments ? If not , why ?
Answer: 663
663-861Gold 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: 664
What is electronegativity ? Write its unit .
Answer: 664
664-861The ability of an atom to attract the shared pair of electrons towards itself in a molecule is called electronegativity
Question: 665
Write down two properties of gold
Answer: 665
665-8611: Gold is a yellow sift metal
2: It is most malleable and ductile of all the metals
Question: 666
What is difference between steel and stainless steel ?
Answer: 666
666-861Steel : Alloy of iron with other metals called steel
Question: 667
Why is naphthalene soluble in carbon tetrachloride and not in water ?
Answer: 667
667-861Non -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: 668
Give difference between solution and colloids .
Answer: 668
668-861Colloids :
The particles of colloids are large consisting of many atoms , ions , or molecules
Question: 669
Why is HF a weak acid ?
Answer: 669
669-861HF less ionizes , hydrogen bond is present between its molecules . That is why it is a weak acid
Question: 670
What ammendment was made by H.Moseley in mendeleev periodic table ?
Answer: 670
670-861According 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: 671
Which factors affect the non-metallic character ?
Answer: 671
671-861Non-metallic character depends upon Electron affinity and electronegativity
Question: 672
Why do non-metals accept electron readily ?
Answer: 672
672-861Non-metals have high electronegativity , can accept electrons readily in order to complete their last (valence ) shells
Question: 673
Write ant two chemical properties of non-metals .
Answer: 673
673-8611 : Non-metals usually do not react with water
2: They do not react with dilute acids because non-metals are itself electron acceptors
Question: 674
Write down two significance of non-metals
Answer: 674
674-8611: 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: 675
Calculate the oxidation number of chlorine in KClO3 .
Answer: 675
675-861{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: 676
For what purpose , Iodine-131 is used ?
Answer: 676
676-861Isotopes of iodine I-131 is used to diagnose goiter in thyroid
Question: 677
What is difference between group and period ?
Answer: 677
677-861Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
Question: 678
How many groups and period and periods are there in modern periodic table
Answer: 678
678-8611: Long form of periodic table consists of seven horizontal rows called periods
Question: 679
Why the boiling point of water higher than alcohol?
Answer: 679
679-861Water 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: 680
Why size of an atom decreases from left to right in the periodic table?
Answer: 680
680-861When 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: 681
What are non - electrolytes .Give one example
Answer: 681
681-861The 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: 682
Two hydrogen atoms combine to form molecules H2 while 'He' atom remains monatomic . Explain ?
Answer: 682
682-861Two 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: 683
Name the elements of first group .
Answer: 683
683-8611: Hydrogen (H)
Question: 684
Why ionization energy of Na is less than Mg?
Answer: 684
684-861Ionization 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: 685
Explain Dobereiner's triads .
Answer: 685
685-861Dobereiner 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: 686
Define noble gases and give example .
Answer: 686
686-861Elements 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: 687
Why we stir paints thoroughlybefore use ?
Answer: 687
687-861Paint 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: 688
Write the symbol of noble gasses
Answer: 688
688-8611: Helium (He)
Question: 689
What is an electron affinity ? Give an example .
Answer: 689
689-861Trend 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: 690
Give chemical reaction of methane with chlorine in bright light .
Answer: 690
690-861In bright light (sun light) Cl2 react with CH4 violently and explosively
Chemical reaction : CH4 +2Cl2 ➜ C+4HCL
Question: 691
What are the elements arranged in group 3 to 12 called ?
Answer: 691
691-861The groups 3 to 12 are called transition elements . In these elements 'd ' sub shell is in the process completion
Question: 692
How chlorine chemical react with dilute ?
Answer: 692
692-861Chlorine react withcold dilute NaCl to give sodium hypochlorite
2NaOH +Cl2 ➜ NaCl +NaOCL + H2O
Question: 693
What is difference between valency and oxidation ?
Answer: 693
693-861Valency : Valency is the combining capacity of an atom with other atoms . It depends upon the number of electrons in the outermost shell
Question: 694
In what conditions H2 reacts with l2 ? Give equation of the reaction .
Answer: 694
694-861H2 reacts with l2 on heating and in the presence of catalyst to produce hydrogen iodide
H2 + l2 ➜ 2Hl
Question: 695
What are trends of ionization energy in periodic table ?
Answer: 695
695-861Ionization energy increases from left to right in the period while it decreases from to bottom in a group
Question: 696
Which factor controls the non-metallic character of the element?
Answer: 696
696-861The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity
Question: 697
Why nitrogen is necessary for safety of life on earth ?
Answer: 697
697-861Nitrigen 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: 698
Define effective nuclear charge .
Answer: 698
698-861In 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: 699
What happens at cathode in galvanic cell ?
Answer: 699
699-861Reduction process takes place at cathode in galvanic cell
Cu+2 + 2e➜ Cu
Question: 700
Why test tube becomes cold when KNO3 is dissolved in water ?
Answer: 700
700-861The dissolution of KNO3 in water is an endothermic process in which heat absorbed when KNO3 dissolve in test tube it becomes cold
Question: 701
Name the metal which is the poorest conductor of heat ?
Answer: 701
701-861Lead is the poorest conductor of heat
Question: 702
Write any four examples of colloidal solution .
Answer: 702
702-8611: Starch
Question: 703
Define ionization energy .
Answer: 703
703-861Ionization 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: 704
Define non polar covalent bond and give example .
Answer: 704
704-861Non polar covalent bond is formed between two similar atoms the hsred pair of electrons is attracted by both the atom equally
Question: 705
Why elements are called s and p block elements ?
Answer: 705
705-861Elements are called s and p block elementsbecause their last element is present in s and p sub shell
Question: 706
Magnesium has electronic configuration 2,8,2 .Why magnesium tend to lose electron ?
Answer: 706
706-861electronic 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: 707
What is the shape of cathode in the Nelson's cell ? Why is it perforated ?
Answer: 707
707-861The cathode in Nelson's cell is U- shaped . It is perforated for the percolation of NaoH into a catch basin
Question: 708
Define hydrogen bonding ?
Answer: 708
708-861Th 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: 709
Give the reason for the decrease of electronegatively in down the group .
Answer: 709
709-861Electronegatively decreases down a group because size of the atom increases . The attraction for the shared pair of electrons weakens
Question: 710
What is galvanizing ?
Answer: 710
710-8611: The process of coating a thin layer of zinc on iron is called galvanizing
Question: 711
Identify a strong and weak electrolyte among the following compound
- CuSO4 , Ca (OH)2 , HCL , HNO3
Answer: 711
711-861Strong electrolyte :HCL ,HNO3 AND CuSO4 are strong electrolyte
Question: 712
What is difference between short period and ling period ?
Answer: 712
712-861Short period : First period of periodic table is called short period . It consists of Hydrogen and Helium
Question: 713
Why noble gases are not reactive ?
Answer: 713
713-861The 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: 714
What is difference between colloidal and suspension ?
Answer: 714
714-861Colloid : 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: 715
Describe difference between true solution and colloid .
Answer: 715
715-861True 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: 716
Difference between substance and mixture.
Answer: 716
716-861Substance: A piece of matter in pure form is termed as substance.
e.g. Glucose (C6H12O6) Oxygen
Question: 717
Define chemical bond and write names of its type .
Answer: 717
717-861A 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: 718
Why magnesium is harder than sodium?
Answer: 718
718-861Magnesium 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: 719
Write symbol of any four elements of halogen .
Answer: 719
719-8611: Flourine (F)
Question: 720
Define electrochemistry .
Answer: 720
720-861Electrochemistry is a branch of chemistry that deals with the relationship between electricity and chemical reaction
Question: 721
Why HF is a weak acid ?
Answer: 721
721-861HF 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: 722
Why shielding effect of electron makes cation formation easy ?
Answer: 722
722-861Shielding 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: 723
How can you justify that milk is a colloid?
Answer: 723
723-861Milk 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: 724
Write two physical properties of magnesium .
Answer: 724
724-861Magnesium is good conductor of heat and electricity
Question: 725
Define oxidation and reduction reaction .
Answer: 725
725-861Oxidation: Oxidation is defined as addition of oxygen or removal of hydrogen or electron during a chemical reaction
Question: 726
Give two examples of suspension .
Answer: 726
726-8611: In suspension the undissolved particles are big enough to be seen with the naked eye
Question: 727
Define Bond pair ?
Answer: 727
727-861The valence electrons which take part in covalent bond is called bonding electrons . These electrons present in the incomplete valence shell
Question: 728
Write down the reaction occuring on cathode and anode during the electrolysis of water .
Answer: 728
728-861Following reactions occur at anode and cathode during electrolysis of water
Question: 729
Why does covalent bond become polar?
Answer: 729
729-861If 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: 730
Define shielding effect , Describe its trend in a period
Answer: 730
730-861Shielding 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: 731
Which is most precious metal ?
Answer: 731
731-861The most precious metal is platinum
Question: 732
What do you mean by malleable and ductile ?
Answer: 732
732-861Malleability 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: 733
What is the trend of electronegativity in the period ?
Answer: 733
733-861The 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: 734
What are spontaneous and non- spontaneous reaction ? Differentiate them
Answer: 734
734-861Spontaneous reaction : The reaction which proceed without any external assistance and heat are called spontaneous reaction .These reactions takes place in galvanic cells
Question: 735
Define reduction on the basis of electron and give example .
Answer: 735
735-861Reduction reaction : The gain of electrons by atom or ion is called reduction reaction .
Question: 736
Define single covalent bond and give one example .
Answer: 736
736-861'When one electron is contributed by each bonded atom ,one bond pair is formed and it forms a single covalent bond '
Question: 737
Write chemical reaction that takes place during working of Nelson's cell.
Answer: 737
737-861Following reactions take place in Nelson's cell
Ions formed in Brine
2NaCl (aq)➜ 2Na+ (aq) +2Cl(aq)
Question: 738
Calculate the oxidation number of nitrogen in HNO3 .
Answer: 738
738-861HNO3 = (1) +(N) +3 (-2)
= 1+N-6
N = +5
Question: 739
What is the electronegativity of hydrogen and chlorine ?
Answer: 739
739-8611: Value of electronegativity of hydrogen (H) is 22
Question: 740
Define metallic character .
Answer: 740
740-861The property of a metal to loose its valence electrons to form a positive ion is called metallic character
Question: 741
What is stainless steel?
Answer: 741
741-861Stainless steel is an alloy which is formed by the combination of iron , ,chromium and nickel
Question: 742
Is triple covalent bond stronger than double covalent bond ? Give reason
Answer: 742
742-861In 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: 743
Identify as colloids and suspensions : paints, jelly, soap solution , milk , milk of magnesia , chalk in water .
Answer: 743
743-861Colloid : Soap solution , Milk , Jelly
Suspension : paints , milk of magnesia , chalk in water
Question: 744
Define oxidizing and reducing agents with example .
Answer: 744
744-861Oxidizing 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: 745
Why the trend of electron affinity and electron -negativity same in the period?
Answer: 745
745-861The 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: 746
Differentiate between donor atom and acceptor atom.
Answer: 746
746-861Donor atom : The atom which donates the electron pair in coordinate covalent bond is called donor atom
Question: 747
Differentiate between molecular mass and formula mass, which of the following will be molecular formula?
Answer: 747
747-861H2O,NaCl, KI, H2SO4
Question: 748
What is the relationship between electro positivity and ionization energy ?
Answer: 748
748-861Electronegativity depends upon the ionization energy which is in turn depends upon size and nuclear charge of the atom
Question: 749
Why does oxygen molecule not form a polar covalent bond ?
Answer: 749
749-861In 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: 750
What do you means by 24 carat gold ?
Answer: 750
750-8611: Purity of gold is show by carats .
Question: 751
How electro positivity depends upon size and nuclear charge of an atom?
Answer: 751
751-861Electropositivity 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: 752
Determine the oxidation number of Mn in KMnO4.
Answer: 752
752-861{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: 753
Which metals are the most malleable and ductile ?
Answer: 753
753-861Gold (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: 754
Differentiate between ionic bond and covalent bond .
Answer: 754
754-861Ionic 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: 755
Why sodium metal is more reactive than magnesium metal?
Answer: 755
755-861Sodium 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: 756
What is meant by dipole dipole forces of attraction ?
Answer: 756
756-861When 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: 757
What are metalloides ? Gibe two examples
Answer: 757
757-861The elements have characteristics of both metals and non-metals are called metalloids
Question: 758
How will you test weather given solution is colloidal solution or not ?
Answer: 758
758-861Colloidal solution show tyndall effect and other solutions do not show tyndall effect
Question: 759
What are electrolytic cell ?
Answer: 759
759-861Electrolytic 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: 760
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: 760
760-861All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state
Question: 761
Write any two properties of solution and suspension
Answer: 761
761-861Solution :
1: A solution is a homogeneous mixture of two or more substances
Question: 762
Define electrolyte . Give an example .
Answer: 762
762-861Electrolyte : The substance which can conduct electricity in their solution or molten states are called electrolytes . Salts and acids are good electrolytes
Question: 763
Give uses of platinum
Answer: 763
763-861Uses of platinum :
1: Platinum is used in hard disk coating and in maufacturing fibre optic cables
Question: 764
Why electro positivity decreases from left to right in a period?
Answer: 764
764-861Electropositivity 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: 765
What are difference between string and weak electrolytes .
Answer: 765
765-861Strong electrolyte : The substance which ionizes completely in solution to produce more ions which can conduct strongly is called strong electrolyte
Question: 766
Why oxygen is called non-metal?
Answer: 766
766-861Non-metals form negative ions by gaining electrons. Oxygen atoms can accept 2 electrons therefore its valency is 2. 0+2e-➜0-2
Question: 767
Define polar covalent bond with example .
Answer: 767
767-861Polar 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: 768
Which metal is used for metal work?
Answer: 768
768-861As 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: 769
Write four physical properties of calcium metals .
Answer: 769
769-8611: Calcium is silvery grey and fairly harder metal
Question: 770
Why do suspensions not form the homogeneous mixture ?
Answer: 770
770-861The 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: 771
What is pacemaker ?
Answer: 771
771-861A 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: 772
Why fluorine is more non-metallic than chlorine ?
Answer: 772
772-861Fluorine is more reactive than chlorine because the electronegativity of fluorine is greater tahn chlorine
Question: 773
What is the nature of metal oxide?
Answer: 773
773-861When metals react with oxygen they form metallic oxide, which are basic in nature. 2Mg+02➜2Mg0
Question: 774
Why ionization energy ok alkaline earth metals is higher than alkali metals?
Answer: 774
774-861The size of alkali metals is samaller than alkaline earth metals that's why they have high ionization energy
Question: 775
Write any two rules for assigning oxidation number .
Answer: 775
775-8611: The oxidation number (O.N) of an ion consisting on a single element is the same as the charge on that ion .
Question: 776
iodine exists in solid state, can it be beaten with hammer to form sheets?
Answer: 776
776-861No, only solid metals have the characteristic to be beaten with hammer to for sheet
Question: 777
Why O2 is necessary for rusting ?
Answer: 777
777-861Rusting 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: 778
What is the difference between steel and stainless steel ?
Answer: 778
778-861Steel is a mixture while stainless steel is an alloy
Question: 779
Write two properties of silver
Answer: 779
779-8611: Silver is a white Lustrous metal
2: Silver is good conductor of heat and electricity
3: Silver is a very malleable and ductile
Question: 780
In electroplating of silver , from which electrolyte Ag+ comes and where they deposit ?
Answer: 780
780-861In the electrolyte of silver (Ag)+ comes from anode and deposit on cathode .
Question: 781
What are electrolytes or non-electrolytes ?
Answer: 781
781-861Electrolytes : The electrolytes which can conduct electricity in their aqueous solution of fuse form and produce more ions are called electrolytes
Question: 782
Why does chlorine accept an electron and attain -1 charge ?
Answer: 782
782-861Chlorine 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: 783
Ice floats on the surface of water . Give reason.
Answer: 783
783-861Floating 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: 784
Why do ionic compound conduct electricity in solution form . Give reason
Answer: 784
784-861Ionic 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: 785
hat is the importance of oxygen and carbon dioxide for plants and animals ?
Answer: 785
785-861Life 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: 786
Define halogens . give example .
Answer: 786
786-861Halogens : The element of group 17 called halogens
Example : Chlorine , Fluorine , Bromine etc
Question: 787
Write difference between electrolytic cell and galvanic cell.
Answer: 787
787-861Electrolytic 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: 788
Can liquid and gases be brittle?
Answer: 788
788-861No, Only solid non-metals are brittle.
Question: 789
Identify strong or weak electrolyte among the following
CuSO4 , H2CO3 ,(OH)2 , AGNO3 , Ca (OH)2
Answer: 789
789-861Strong electrolyte :HCL,HNO3 and CuSO4. AgNO3 are strong electrolyte
Question: 790
How oxygen react with group-2 metals?
Answer: 790
790-861They are less reactive towards oxygen and oxides are formed on heating
Question: 791
What does mean rusting of iron ?
Answer: 791
791-861Corrosion of iron is called rusting . The important condition for rusting is moist air
Question: 792
Write four physical properties of metals
Answer: 792
792-8611: Almost all metals are solid (Except mercury)
Question: 793
Why calcium is more electropositive than to magnesium?
Answer: 793
793-861Calcium 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: 794
What is salt bridge ? What is its basic function ?
Answer: 794
794-861Galvanic cell consists of two half cells, both these half cells are connected by salt bridge
Question: 795
Give chemical reaction of H2 and Cl2 and l2Reaction of H2 with Cl2 :
Answer: 795
795-861H2 reacts with Cl2 only in the presence of sunlight
H2 + Cl2 ➜ 2HCL
Question: 796
Define brine ?
Answer: 796
796-861The by-product in Nelson's cell are hydrogen gas (H2) and chlorine gas (Cl2)
Question: 797
Why is gold used to make jewelry?
Answer: 797
797-861Gold 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: 798
Differentiate between polar and non polar covalent bond .
Answer: 798
798-861Polar 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: 799
What is difference between corrosion and rusting ?
Answer: 799
799-861Corrosion : 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: 800
How iron is prevented from rust by tin coating ?
Answer: 800
800-8611:It involves the dipping of the clean sheet of iron in a bath of molten tin and then passing it through hot rollers
Question: 801
How platinum is used as a catalyst in automobiles and what are advantages of this use ?
Answer: 801
801-861Platinum alloyed with palladium and rhodium is used as a catalyst in automobile as catalyst converter . It converts harmful gases into harmless gases
Question: 802
Define alloy and give example .
Answer: 802
802-861Alloy : alloy is a homogeneous mixture of one metal with one or more metals or non-metals
Question: 803
How galvanizing of iron sheets is done ?
Answer: 803
803-861The 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: 804
What is meant by electroplating ?
Answer: 804
804-861Electroplating is depositing of one metal over the other by means of electrolysis
Question: 805
Write down the name of four least reactive metals .
Answer: 805
805-861The names of least reactive metals are following
Question: 806
What is galvanic cell? Give an example .
Answer: 806
806-861The electrochemical cell in which a spontaneous chemical reaction takes place and generates electric current is called galvanic or voltaic cell
Question: 807
Write the redox reaction taking place during the electroplating of chromium .
Answer: 807
807-861Chromium 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: 808
Calculate the oxidation number of Sulphur (S) in H2SO4
Answer: 808
808-861H2SO4 = 2(+1) +(S) +4(-2)
=2=S-8
S = +6
Question: 809
Give application of silver ?
Answer: 809
809-8611: Compound of silver are widely used in photographic films
Question: 810
Define metal and give two examples .
Answer: 810
810-861The elements which have ability to lose electron and forms cations called metals like Na , K , Ca
Question: 811
Name the best ductile and malleable metal ?
Answer: 811
811-861Gold and silver
Question: 812
Why sodium metal is more reactive than magnesium ?
Answer: 812
812-861Magnesium 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: 813
Write names of any two noble metals
Answer: 813
813-8611: Copper
Question: 814
Why is platinum is used to make jewelry ?
Answer: 814
814-861Platinum 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: 815
Which solution is used as an electrolyte in Nelson's cell ?
Answer: 815
815-861In Nelson cell concentrated solution of sodium chloride is used . It is called brine solution
Question: 816
What is meant by malleable and ductile metals ?
Answer: 816
816-861Malleable : The substance that can be drawn into sheets are called malleable
Question: 817
Why nitrogen forms compounds with alkaline earth metals directly ?
Answer: 817
817-861A alkaline earth metals from stable nitrides when heated with nitrogen
Question: 818
Name the metal which is least conductor of heat ?
Answer: 818
818-861Lead is a metal which is least conductor of heat
Question: 819
What is metallic coating ?
Answer: 819
819-861For the protection against the rusting metals are coated with other metal and it is called metallic coating.
Question: 820
Describes the trends of electropositivity in a period and in a group .
Answer: 820
820-861Electropositive 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: 821
Complete the following chemical equation .
Answer: 821
821-861NaO +H2O➜ 2NaOH