10th Class Chemistry Chapter 4 Short Questions with Answers Solved

Question: 1

What is the difference between a straight and a branched chain hydrocarbons ?

Answer: 1

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Straight hydrocarbons : Straight chain compound are those in which carbon atoms are linked with each other through double and triple bonds forming a straight chain

H₃C-CH₂-CH₂-CH₃

_{Straight chain (n-butane )}

Question: 2

Give the reduction of alkyl halide.

Answer: 2

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Reduction means addition of nascent hydrogen. It is a replacement of a halogen atom with hydrogen atom in the presence of Zn metal and HCl

Question: 3

Define hydrocarbons.

Answer: 3

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Hydrocarbons are those compounds which are made up of only carbon and hydrogen elements.

Question: 4

Give some uses of alkynes .

Answer: 4

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1: It is also used for artificial ripening of fruits

Question: 5

Define saturated hydrocarbons with examples .

Answer: 5

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The hydrocarbons in which al the four valencies of carbon atoms are fully satisfied (saturated) by single bonds with other carbon atoms and hydrogen atoms are called saturated hydrocarbons . Saturated hydrocarbons are also called alkanes . Thus , an alkane is a hydrocarbon in which the carbon atoms are connected by only single covalent bond (there are no double or triple covalent bonds in alkanes

Methane (CH₄) , Ethane (C₂H₆ ) , propane (C₃H₈) and butane (C₄H₁₀) are all saturated hydrocarbons because they contain only carbon-carbon single bonds

Question: 6

Give few uses of ethene.

Answer: 6

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Ethene is used for artificial ripening of fruits Use as a general anaesthetic for manufacture of polythene

Question: 7

Why are hydrocarbons considered as parent organic compounds ?

Answer: 7

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Hydrocarbons are regarded as the parent organic compounds since other organic compounds are considered to be derived from them by the replacement of one or more hydrogen atoms by other atoms or groups of atoms

Question: 8

Different between saturated and unsaturated hydrocarbons.

Answer: 8

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Saturated hydrocarbon:Thy hydrocarbons in which all four valences electrons of carbon atoms are fully satisfied by single bonds with other carbon atoms and hydrogen atoms are called saturated hydrocarbons.

Question: 9

Give a test used to identify unsaturation of an organic compound

Answer: 9

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Dissolve about 0.2 if organic compound in water in a test tube .add 2-3 drops of alkanes KMnO₄solution in it shake the disappearance of pink color indicates the presence of unsaturation in the organic compound

Question: 10

Why alkanes are called paraffins?

Answer: 10

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Inalkanes al the bonds of carbon atoms are single that means valences electrons of carbon atoms are saturated.There fore they are least reactive that is the reason, alkanes are called parafins.

Question: 11

Why are the alkanes used as fuel ?

Answer: 11

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Alkanes burn in the presence of excess of air or oxygen to produce a lot of heat , carbon dioxide and water . This reaction takes place in automobile combustion engines , domestic heaters and cooking appliances . It is highly exothermic reaction and because of it alkanes are used as fuel

CH₄+ 2O₂→ CO₂ +2H₂O +heat

Question: 12

Why alkenes are known as olefins?

Answer: 12

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Alkenes are known as olefins because first members of alkenes form oily products when react with halogens. Olefins means oil forming.

Question: 13

Physical properties of alkanes.

Answer: 13

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Physicsl state: Alkanes form a homologous series of compounds and first four members of the sereis are gases. the alkanes consisting of C3 to C10 are liquid while the higher members are solids.

Question: 14

Why are alkenes reactive ?

Answer: 14

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Alkenes are reactive compounds because the electrons of the double bond are easily available for reaction

Question: 15

Why are hydrocarbons soluble in organic solvents ?

Answer: 15

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Hydrocarbon are soluble in organic solvents because both of them are non polar covalent compounds the principle of solubility is like dissolve like

Question: 16

What is Rubber industry?

Answer: 16

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Hydrocarbons are used to prepare synthetic rubber , such as acetylene is used to prepare butadiene rubber used for making footwear, tyres and toys. similarly, a good quality rubber neoprene is prepared from chloroprene.

Question: 17

What is the simplest alkane ?

Answer: 17

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Methane is the simplest alkane CH₄

Question: 18

What do you mean by halogenations?

Answer: 18

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A reaction in which one or more hydrogen atoms of a saturated compounds are replaced with halogen atom is called halogenations.

Question: 19

Identify propane from propane with a test?

Answer: 19

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Propane and propane can be identified by bromide water test . propane does not give bromine water test because it is saturated hydrocarbons . While propene decolorized the bromine water because propane is unsaturated hydrocarbon having double bond

Question: 20

What is petrochemical industry.

Answer: 20

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The organic compounds prepared from hydrocarbons are called petrochemicals. some of the important petrochemicals are methyl alcohol, ethyl alcohol,formic acid, chloroform, carbon tetrachloride, ethylene, butadiene, benzene, toluene,etc.

Question: 21

Give the physical properties of alkanes .

Answer: 21

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Solubility : They are non-polar , therefore , they are insoluble in water but soluble in organic solvents

Density : The density of alkanes increases gradually with the increase of molecular size

Question: 22

What is Synthetic fibre industry.

Answer: 22

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Hydrocarbons are used to prepare synthetic fibres like nylon. rayon polyesters these fibres have better qualities like greater strength good clasticity, resistance to wear and tear.

Question: 23

Why the alkynes are called acetylenes

Answer: 23

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Alkynes are also called acetylenes because of the name of the first member of the series id acetylene

Question: 24

Justify the alkane give substitution reaction

Answer: 24

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A reaction in which one or more hydrogen atoms of a saturated compound are replaced with some other atoms (like halogen) is called a substitution reaction . Because alkanes has single bonds not double bonds so it do not add more atoms , it give substitution reaction

Question: 25

What is plastic industry.

Answer: 25

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Hydrocarbons are used as raw materials for the preparation of a large variety of synthetic polymers Called plastics like polythene, polyester. These can be given any shape when soft and on hardening make a durable article to be sued in electric and sewages items and a lot of other household items in common life.

Question: 26

Why the burning of alkanes require sufficient supply of oxygen ?

Answer: 26

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Alkanes burn in the presence of excess of air or oxygen to produce a lit of heat , carbon dioxide and water . This reaction takes place in automobile combustion engines , domestic heaters and cooking appliances . It is highly exothermic reaction and because of it alkanes are used as fuel

CH₄ +2O₂→ CO₂ +2H₂O +heat

Question: 27

What do you mean by halogenation ? Give the reaction of methane with chlorine in bright sunlight .

Answer: 27

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Halogenation in which one or more hydrogen atoms of a saturated compound are replaced with halogen atom is called halogenation reaction

CH₄ + 2CL₂ → C+₄HCL

Question: 28

Give a few uses of ethane .

Answer: 28

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Ethane is used

1: for a artificial ripening of fruits

2: as a general anaesthetic

3: for manufacture of polythene : Polythene is a plastic material used in packaging , toys , bags etc ethyl alcohol , ethylene, glycol, diethyl ether etc ; ethylene oxide is used as a fumigant , ethylene glycol is used as an anti-freeze , diethyl ether and ethyl alcohol are used as solvents and

4: for making poisonous mustard gas which is used in chemical warfar

Question: 29

How can you identify ethene from ethene ?

Answer: 29

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We identify ethene from ethene by bromine water test , ethane does not give bromine water test while ethane decolourized the bromine water because ethene is saturated and ethane is unsaturated hydrocarbon

Question: 30

What is Synthetic detergents.

Answer: 30

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Long chain hydrocarbons obtained from petroleum are used to make synthetic detergents and washing powders. These detergents are sodium salts of alkyl hydrogen sulphate. These detergents have better and stronger cleaning properties than that of sofaps. They can be used even in hard water.

Question: 31

Why hydrocarbon used as a fuel

Answer: 31

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The main constituent of fuels (coal , petroleum and natural gas ) are hydrocarbons . When hydrocarbons are burnt in air the reaction is called combustion . It is highly exothermic reaction , i-e it produces a lot of heatThe basic combustion reaction isCH4 + 2O2? CO2 + 2H2O + heat

Question: 32

Why colour of bromine water discharge on addition of ethane in it ?

Answer: 32

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When bromine water (a solution of bromine in water having red-brown color ) is added to ethane in an inert solvent like carbon tetrachloride , its color is discharges at once

Question: 33

State one important use of each .

Answer: 33

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Ethene : Ethene is used for artificial ripening of fruits

Acetylene : Acetylene is used to prepare other chemicals , such as alcohols , actaldehyde and acids

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10th Class Chapter 4 Chemistry Short Questions

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