Free Chemistry of Hydrocarbons MCQs with Answers

• A. Alkyl free radical
• B. Carbanion
• C. Carbocation
• D. Methylpropane

Explanation: The homolytic fission of one C-H bond produces a methyl radical (•CH₃) and a hydrogen radical (•H).

• A. isobutyl bromide
• B. n-butyl bromide
• C. sec-butyl bromide
• D. tert-butyl bromide

Explanation: The addition of HBr to isobutylene predominantly yields tert-butyl bromide because the reaction proceeds through a carbocation…

• A. Butane
• B. Propane
• C. Methane
• D. Ethane

Explanation: Methane is the most abundant component of natural gas.

• A. four
• B. five
• C. six
• D. seven

Explanation: Ethane (C2H6) has one C-C single bond and six C-H single bonds, totaling seven bonds.

• A. single
• B. double
• C. triple
• D. quadruple

Explanation: Alkanes are saturated hydrocarbons with only single bonds between carbon atoms.

• A. Methanol
• B. Acetylene
• C. Benzene
• D. Acetic acid

Explanation: Benzene is the simplest and parent aromatic hydrocarbon.

• A. Aryl
• B. Alkyl
• C. Alkenyl
• D. Phenyl

Explanation: Removing a hydrogen from an alkane forms an alkyl group.

• A. Hexylchloride
• B. 3-chloromethylhexane
• C. 3-chloro-3-ethylbutane
• D. 3-chloro-3-methylpentane

Explanation: The longest chain is 5 carbons (pentane), and the substituents are at the 3rd carbon.

• A. HCl
• B. Chloroform
• C. Hexachlorobenzene
• D. Polyvinyl chloride (PVC)

Explanation: In the presence of sunlight, benzene undergoes an addition reaction with chlorine to form hexachlorocyclohexane (hexachlorobenzene).

• A. F₂
• B. I₂
• C. Cl₂
• D. Br₂

Explanation: I₂) - Correct: Iodine is the least reactive because it forms a weak I-C bond, making the reaction slow

• A. (C₂H₅)₄Pb
• B. (CH₃)₄Pb and TiCl₄
• C. Al(C₂H₅)₃ and TiCl₄
• D. Zn/HCl

Explanation: Al(C₂H₅)₃ and TiCl₄) - Correct: This is the Ziegler-Natta catalyst, which promotes ethene polymerization.

• A. Ethanenitrile
• B. Acrylonitrile
• C. Ethyl nitrile
• D. Methyl alcohol

Explanation: Ethyl nitrile) - Correct: Ethyl nitrile (C₂H₅CN) is the correct product.

• A. Maleic anhydride
• B. Benzoic acid
• C. Benzyl alcohol
• D. Benzaldehyde

Explanation: Benzoic acid) - Correct: Toluene oxidizes to benzoic acid (C₆H₅COOH)

• A. Bromination in sunlight
• B. Catalytic oxidation
• C. Bromination with Fe and Br₂
• D. Oxidation by acidified KMnO₄

Explanation: Oxidation by acidified KMnO₄) - Correct: Acidified KMnO₄ decolorizes if benzene contains unsaturated side chains, confirming unsaturation.

• A. Non thermic reaction
• B. Exothermic reaction
• C. Endothermic reaction
• D. None

Explanation: During Sabatier-Sendern reaction, hydrogenation of alkene occurs, that breaks the doubke bond to produce single bond.

• A. But-1-yne
• B. But-1-ene
• C. But-2-yne
• D. But-2-ene

Explanation: Ammonical AgNO3 forms white ppt. with aldehydes and terminal alkynes. This is also known as the silver mirror test.

• A. Baeyer's reagent
• B. Ammonical AgNO3
• C. Br2 solution
• D. O3, Zn / H2O

Explanation: Ozonolysis of these will give different products which can differentiate between but-1-ene and 2-methyl propene.

• A. 2-butene
• B. 1-butyne
• C. 2-butyne
• D. Both B and C

Explanation: Kolbe electrolysis is an electrochemical decarboxylation of the salts of carboxylic acid which produces radicals.

• A. Alkene
• B. Alkyne
• C. Alkane
• D. Amine

Explanation: In the Wolff-Kishner reduction, carbonyl compound is converted into alkane by intermediate hydrazone.

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: This reaction involves the alkyne HC≡CH (acetylene), carbon monoxide (CO), methanol (CH3OH), and nickel tetracarbonyl (Ni(CO)4).