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Hydrocarbons WBJEE MCQ & Practice Questions

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Hydrocarbons Revision Guide for WBJEE Chemistry

Hydrocarbons is part of WBJEE Chemistry preparation. A strong revision plan should combine concept review with exam-style questions so that definitions, relationships, calculations and exceptions are recalled accurately.

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Important Topics

  • Core definitions and principles
  • Important equations or relationships
  • Common applications and examples
  • Frequently confused concepts
  • Exam-style multiple-choice questions
  • Error review and targeted revision

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Create a one-page summary of trends, structures, reactions, exceptions and key terminology for Hydrocarbons, then test recall with mixed MCQs.

What to practise in Hydrocarbons

Concept Revision

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Exam-style MCQs

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Top 20 Hydrocarbons MCQs with Answers

These public questions are selected from the exact Hydrocarbons chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

1. Ethane is obtained by hydrogenation of:

  • A. Ethanal
  • B. Ethanoic acid
  • C. Ethene
  • D. Ethanol
Answer: C
Explanation: Hydrogen adds across the C=C bond of ethene to form ethane.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

2. Wurtz reaction is useful for preparing:

  • A. Carboxylic acids
  • B. Higher alkanes
  • C. Alcohols
  • D. Aldehydes
Answer: B
Explanation: Alkyl halides couple with sodium in dry ether to form alkanes.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

3. Methane reacts with chlorine in sunlight mainly by:

  • A. Free-radical substitution
  • B. Electrophilic addition
  • C. Nucleophilic addition
  • D. Elimination
Answer: A
Explanation: Photochemical chlorination of methane proceeds by a radical chain mechanism.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

4. Complete combustion of a hydrocarbon gives:

  • A. CO and H2 only
  • B. C and H2
  • C. CH3OH only
  • D. CO2 and H2O
Answer: D
Explanation: Complete combustion converts carbon to CO2 and hydrogen to water.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

5. Ethene decolourises bromine solution because it undergoes:

  • A. Condensation
  • B. Hydrolysis
  • C. Addition
  • D. Substitution only
Answer: C
Explanation: Bromine adds across the carbon-carbon double bond.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

6. Hydration of ethene under acidic conditions produces:

  • A. Ethane
  • B. Ethanol
  • C. Ethanal
  • D. Ethanoic acid
Answer: B
Explanation: Water adds across the C=C bond to form ethanol.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

7. Ozonolysis is especially useful for locating:

  • A. Carbon-carbon multiple bonds
  • B. Only C-H bonds
  • C. Only O-H bonds
  • D. Ionic bonds
Answer: A
Explanation: Cleavage products reveal the positions/substitution of multiple bonds.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

8. Ethyne contains:

  • A. Three sigma bonds
  • B. Two sigma and one pi bond
  • C. Three pi bonds
  • D. One sigma and two pi bonds between the carbons
Answer: D
Explanation: A carbon-carbon triple bond consists of one sigma and two pi bonds.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

9. Terminal alkynes are weakly acidic because the acidic hydrogen is attached to:

  • A. sp3 carbon
  • B. oxygen
  • C. sp carbon
  • D. sp2 carbon
Answer: C
Explanation: The high s-character of sp carbon stabilises the acetylide ion.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

10. Benzene preferentially undergoes:

  • A. Radical polymerisation
  • B. Electrophilic substitution
  • C. Electrophilic addition
  • D. Nucleophilic addition
Answer: B
Explanation: Substitution preserves aromaticity.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

11. Nitration of benzene uses concentrated HNO3 with:

  • A. Concentrated H2SO4
  • B. NaOH
  • C. NH3
  • D. H2O2 only
Answer: A
Explanation: Sulfuric acid generates the nitronium electrophile.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

12. The electrophile in benzene nitration is:

  • A. NO3-
  • B. NH2-
  • C. OH-
  • D. NO2+
Answer: D
Explanation: Nitronium ion attacks the aromatic ring.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

13. Chlorobenzene is less reactive than chloroethane toward nucleophilic substitution mainly because:

  • A. Benzene is nonpolar
  • B. Chloroethane is aromatic
  • C. C-Cl has partial double-bond character
  • D. Chlorine is absent
Answer: C
Explanation: Resonance strengthens the aryl C-Cl bond.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

14. Finkelstein reaction is commonly used to prepare:

  • A. Amines
  • B. Alkyl iodides
  • C. Alcohols
  • D. Ketones
Answer: B
Explanation: Alkyl chlorides/bromides react with NaI in acetone.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

15. Swarts reaction is associated with preparation of:

  • A. Alkyl fluorides
  • B. Alkyl iodides
  • C. Alcohols
  • D. Aldehydes
Answer: A
Explanation: Metal fluorides replace Cl/Br by F.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

16. SN1 reactions proceed through a:

  • A. Carbanion intermediate
  • B. Free radical only
  • C. Carbene only
  • D. Carbocation intermediate
Answer: D
Explanation: Unimolecular ionisation first forms a carbocation.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

17. SN2 reactions proceed by:

  • A. A radical chain
  • B. Electrophilic aromatic substitution
  • C. One-step backside attack
  • D. A free carbocation intermediate
Answer: C
Explanation: Bond formation and bond cleavage occur concertedly.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

18. SN2 reaction at a chiral carbon characteristically gives:

  • A. No stereochemical change
  • B. Inversion of configuration
  • C. Complete retention always
  • D. Racemisation only
Answer: B
Explanation: Backside attack produces Walden inversion.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

19. Tertiary alkyl halides generally favour SN1 over primary halides because:

  • A. Tertiary carbocations are more stable
  • B. They are less substituted
  • C. They cannot ionise
  • D. They have no carbon-halogen bond
Answer: A
Explanation: Carbocation stability facilitates the rate-determining ionisation.

WBJEE Chemistry · Hydrocarbons · Very Very Hard

20. Primary alcohol oxidation under controlled conditions can give:

  • A. Ketone only
  • B. Alkane
  • C. Ether only
  • D. Aldehyde
Answer: D
Explanation: Mild oxidation of a primary alcohol yields an aldehyde.

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Hydrocarbons Practice Tests

Hydrocarbons Frequently Asked Questions

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