CBSE Class 11 Chemistry Hydrocarbons MCQs

Question: Which of the following fuel cause the least pollution ?

a) LPG

b) CNG

c) Petrol

d) Kerosene

Answer: LPG

Question: LPG mainly contains

a) butane

b) ethane

c) methane

d) ethyne

Answer: butane

Question: Which of the following gas is find in coal mines and marshy places?

a) Methane

b) Ethane

c) Propane

d) Benzene

Answer: Methane

Question: Two adjacent members of a homologous series have

a) All the above

b) same general method of preparation

c) a different of 14 amu in molecular mass

d) a difference of CH₂ in their structure

Answer: All the above

Question: Methane, ethane and propane are said to form a homologous series because all are

a) differ from each other by a CH₂ group

b) aliphatic compounds

c) saturated compounds

d) hydrocarbons

Answer: differ from each other by a CH₂ group

Question: The number of primary, secondary and tertiary carbons in 3, 4-dimethylheptane are respectively

a) 4, 3 and 2

b) 4, 2 and 3

c) 2, 3 and 4

d) 3, 4 and 2

Answer: 4, 3 and 2

Question: Which of the following statements is false for isopentane

a) It has a carbon which is not bonded to hydrogen

b) It has one CH group

c) It has three CH₃ groups

d) It has one CH₂ group

Answer: It has a carbon which is not bonded to hydrogen

Question: How many isomers are possible for the C₅H₁₂ ?

a) 3

b) 5

c) 2

d) 4

Answer: 3

Question: The number of 4° carbon atoms in 2,2,4,4-tetramethyl pentane is –

a) 2

b) 4

c) 1

d) 3

Answer: 2

Question: Which one of the following cannot be prepared by Wurtz reaction ?

a) CH₄

b) C₂H₆

c) Both

d) None of these

Answer: CH₄

Question: Pure methane can be produced by

a) Soda-lime decarboxylation

b) Reduction with H₂

c) Kolbe’s electrolytic method

d) Wurtz reaction

Answer: Soda-lime decarboxylation

Question: Sodium salts of carboxylic acids on heating with soda lime give alkanes containing _______ than the carboxylic acid

a) one carbon less

b) one carbon more

c) two carbon less

d) All of these

Answer: one carbon less

Question: Which one of the following has the least boiling point?

a) 2, 2– dimethylpropane

b) 2-methylpropane

c) n-butane

d) n-pentane

Answer: 2, 2– dimethylpropane

Question: Which one of the following has highest boiling point?

a) n-Octane

b) Iso-octan

c) 2,2 dimethyl pentane

d) All have equal values

Answer: n-Octane

Question: In the free radical chlorination of methane, the chain initiating step involves the formation of

a) chlorine free radical

b) hydrogen chloride

c) methyl radical

d) chloromethyl radical.

Answer: chlorine free radical

Question: Which one of the following gives only one monochloro derivative?

a) neo-pentane

b) 2-methylpentane

c) n-hexane

d) 2, 3-dimethylpentane

Answer: neo-pentane

Question: Photochemical halogenation of alkane is an example of

a) free radical substitution

b) nucleophilic substitution

c) electrophilic addition

d) electrophilic substitution

Answer: free radical substitution

Question: 2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly

a) 2-bromo-2-methylbutane

b) 1-bromo-2-methylbutane

c) 2-bromo-3-methylbutane

d) 1-bromo-3-methylbutane

Answer: 2-bromo-2-methylbutane

Question: Liquid hydrocarbons can be converted to a mixture of gaseous hydrocarbons by

a) cracking

b) distillation under reduced pressure

c) hydrolysis

d) oxidation

Answer: cracking

Question: n-Hexane isomerises in presence of anhydrous aluminium chloride and hydrogen chloride gas to give

a) Both

b) 2-Methyl pentane

c) 3-Methyl pentane

d) None of these

Answer: Both

Question: How many conformations are possible for ethane ?

a) infinite

b) 2

c) 3

d) one

Answer: infinite