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NEET UG 2020 · Chemistry · Question 133

NEET 2020 Chemistry, question 133

Question 133 of the NEET 2020 paper (code E1) is a Chemistry question from Hydrocarbons. Its idea, Retro-Ozonolysis (Reactant Identification), was asked only this once in NEET 2017–2026. The NTA final answer key gives option 3.

Updated 2026-10-08

Q133 · Chemistry

An alkene on ozonolysis gives methanal as one of the product. Its structure is :

The figure, described in words

All four options are drawn skeletal structures: (1) cyclohexyl-CH=CH-CH3; (2) and (4) cyclohexene rings with an n-propyl group (ring double bond in different positions); (3) cyclohexyl-CH2-CH=CH2.

  1. 1[structure: cyclohexane ring bearing −CH=CH−CH3-\mathrm{CH=CH-CH_3}]
  2. 2[structure: cyclohexene ring (ring C=C) bearing −CH2−CH2−CH3-\mathrm{CH_2-CH_2-CH_3}]
  3. 3[structure: cyclohexane ring bearing −CH2−CH=CH2-\mathrm{CH_2-CH=CH_2}]Official answer
  4. 4[structure: cyclohexene ring (ring C=C) bearing −CH2CH2CH3-\mathrm{CH_2CH_2CH_3}]

Official answer: option 3 · NTA final answer key

Same idea

The only question on Retro-Ozonolysis (Reactant Identification)

No other NEET paper from 2017–2026 tested this exact idea.

Retro-Ozonolysis (Reactant Identification): every question and how it was framed

The chapter

Hydrocarbons in ten years of NEET

25 questions from 2017–2026, asked in 10 of 10 papers, about 2.4 a paper. Hydrocarbons (Alkenes) alone had 12.

Chapter analysisStudy this chapterPractise this chapter

Hydrocarbons: questions per paper

0363’171’182’192’204’212’222’231’245’253’26