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Hydrocarbons NEET Practice Questions & MCQs

Chapter-wise hydrocarbons MCQs for NEET with stepwise answers, short concept notes and practice tests to revise mechanisms and reactions.

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Hydrocarbons Revision Guide for NEET Chemistry

Hydrocarbons is part of NEET 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

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  • 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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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.

NEET Chemistry · Hydrocarbons · Very Hard

1. The number of sigma and pi bonds in ethyne is:

  • A. 3 sigma and 2 pi
  • B. 2 sigma and 3 pi
  • C. 5 sigma and 1 pi
  • D. 4 sigma and 2 pi
Answer: A
Explanation: Ethyne has two C–H sigma bonds and one C–C sigma bond, together with two C–C pi bonds.

NEET Chemistry · Hydrocarbons · Very Hard

2. The hybridisation of each carbon atom in ethene is:

  • A. dsp2
  • B. sp2
  • C. sp
  • D. sp3
Answer: B
Explanation: Each carbon in ethene forms three sigma bonds and one pi bond, corresponding to sp2 hybridisation.

NEET Chemistry · Hydrocarbons · Very Hard

3. Which hydrocarbon has the highest percentage of carbon by mass?

  • A. Ethane
  • B. Methane
  • C. Ethyne
  • D. Ethene
Answer: C
Explanation: For ethyne, carbon percentage is 24/26 × 100, which is greater than that in ethene, ethane or methane.

NEET Chemistry · Hydrocarbons · Very Hard

4. The most stable conformation of ethane is:

  • A. Eclipsed
  • B. Gauche
  • C. Boat
  • D. Staggered
Answer: D
Explanation: The staggered conformation minimises torsional strain and is therefore most stable.

NEET Chemistry · Hydrocarbons · Very Hard

5. The energy barrier to rotation about the C–C bond in ethane is mainly due to:

  • A. Torsional strain in the eclipsed conformation
  • B. Angle strain in the staggered conformation
  • C. Hydrogen bonding
  • D. Aromaticity
Answer: A
Explanation: The eclipsed conformation has repulsion between bonding electron pairs, producing torsional strain.

NEET Chemistry · Hydrocarbons · Very Hard

6. Which reagent converts an alkene into a vicinal dihalide?

  • A. O3 followed by Zn
  • B. Br2 in CCl4
  • C. Aqueous KOH
  • D. NaNH2
Answer: B
Explanation: Bromine adds across the carbon-carbon double bond to form a vicinal dibromide.

NEET Chemistry · Hydrocarbons · Very Hard

7. Addition of HBr to propene in the absence of peroxide mainly gives:

  • A. 1,2-Dibromopropane
  • B. Propan-1-ol
  • C. 2-Bromopropane
  • D. 1-Bromopropane
Answer: C
Explanation: Markovnikov addition proceeds through the more stable secondary carbocation, giving 2-bromopropane.

NEET Chemistry · Hydrocarbons · Very Hard

8. Addition of HBr to propene in the presence of peroxide mainly gives:

  • A. 2-Bromopropane
  • B. 1,2-Dibromopropane
  • C. Propane
  • D. 1-Bromopropane
Answer: D
Explanation: The peroxide effect causes radical anti-Markovnikov addition of HBr, producing 1-bromopropane.

NEET Chemistry · Hydrocarbons · Very Hard

9. The peroxide effect is generally observed with:

  • A. HBr only
  • B. HCl only
  • C. HI only
  • D. All hydrogen halides
Answer: A
Explanation: Only HBr has energetically favourable radical propagation steps for the peroxide effect.

NEET Chemistry · Hydrocarbons · Very Hard

10. Ozonolysis of propene followed by reductive work-up gives:

  • A. Ethanoic acid and methanal
  • B. Methanal and ethanal
  • C. Methanal and methanone
  • D. Ethanal only
Answer: B
Explanation: Cleavage of CH3–CH=CH2 gives CH3CHO and HCHO.

NEET Chemistry · Hydrocarbons · Very Hard

11. Oxidative ozonolysis of ethene ultimately gives:

  • A. Methanol
  • B. Ethanoic acid
  • C. Methanoic acid
  • D. Ethanal
Answer: C
Explanation: Ethene first forms methanal, which is further oxidised to methanoic acid under oxidative work-up.

NEET Chemistry · Hydrocarbons · Very Hard

12. Cold dilute alkaline KMnO4 converts an alkene into:

  • A. An alkyne
  • B. An alkane
  • C. A ketone only
  • D. A vicinal diol
Answer: D
Explanation: Baeyer's reagent adds two hydroxyl groups across the double bond to produce a vicinal glycol.

NEET Chemistry · Hydrocarbons · Very Hard

13. Which alkene is most stable?

  • A. 2-Methylbut-2-ene
  • B. But-1-ene
  • C. Propene
  • D. Ethene
Answer: A
Explanation: Alkene stability increases with alkyl substitution because of hyperconjugation and the +I effect.

NEET Chemistry · Hydrocarbons · Very Hard

14. Which alkene gives only acetone on ozonolysis?

  • A. Propene
  • B. 2,3-Dimethylbut-2-ene
  • C. But-2-ene
  • D. 2-Methylpropene
Answer: B
Explanation: The symmetrical alkene (CH3)2C=C(CH3)2 cleaves to give two molecules of acetone.

NEET Chemistry · Hydrocarbons · Very Hard

15. Hydration of propyne in the presence of HgSO4 and H2SO4 gives:

  • A. Propan-1-ol
  • B. Propanoic acid
  • C. Propanone
  • D. Propanal
Answer: C
Explanation: Markovnikov hydration of propyne forms an enol that tautomerises to propanone.

NEET Chemistry · Hydrocarbons · Very Hard

16. Acetylene on hydration in the presence of HgSO4 and H2SO4 gives:

  • A. Ethanol
  • B. Ethanoic acid
  • C. Ethene
  • D. Ethanal
Answer: D
Explanation: Hydration gives vinyl alcohol, which rapidly tautomerises to ethanal.

NEET Chemistry · Hydrocarbons · Very Hard

17. A terminal alkyne can be distinguished from an internal alkyne using:

  • A. Ammoniacal AgNO3
  • B. Bromine water only
  • C. Baeyer's reagent
  • D. Concentrated H2SO4
Answer: A
Explanation: Terminal alkynes form insoluble silver acetylides with ammoniacal silver nitrate.

NEET Chemistry · Hydrocarbons · Very Hard

18. The acidic character of terminal alkynes is mainly due to:

  • A. Hydrogen bonding
  • B. High s-character of the sp-hybridised carbon
  • C. Resonance of the alkane
  • D. Low electronegativity of carbon
Answer: B
Explanation: An sp carbon has 50% s-character and holds negative charge closer to the nucleus, stabilising the acetylide ion.

NEET Chemistry · Hydrocarbons · Very Hard

19. Which order of acidity is correct?

  • A. Ethene > ethyne > ethane
  • B. Ethyne > ethane > ethene
  • C. Ethyne > ethene > ethane
  • D. Ethane > ethene > ethyne
Answer: C
Explanation: Acidity increases with s-character: sp carbon > sp2 carbon > sp3 carbon.

NEET Chemistry · Hydrocarbons · Very Hard

20. Benzene primarily undergoes substitution rather than addition because:

  • A. Addition is always endothermic
  • B. Benzene has no pi electrons
  • C. Benzene is saturated
  • D. Substitution preserves aromaticity
Answer: D
Explanation: Electrophilic substitution restores and preserves the aromatic sextet, whereas addition destroys aromaticity.

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Hydrocarbons Practice Tests

Hydrocarbons Frequently Asked Questions

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