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Friday, 9 October

NEET UG 2021 · Chemistry · Question 80

NEET 2021 Chemistry, question 80

Question 80 of the NEET 2021 paper (code O1) is a Chemistry question from Hydrocarbons. Its idea, Peroxide Effect (Anti-Markovnikov), was asked only this once in NEET 2017–2026. The NTA final answer key gives option 3.

Updated 2026-10-08

Q80 · Chemistry

The major product of the following chemical reaction is :

(CH3)2CH−CH=CH2+HBr→(C6H5CO)2O2?\mathrm{(CH_3)_2CH-CH=CH_2 + HBr \xrightarrow{(C_6H_5CO)_2O_2} ?}

The figure, described in words

Stem and options: drawn condensed structural formulas (isopropyl-CH-CH=CH2 + HBr reaction and four product structures with branches and Br).

  1. 1(CH3)2CH−CH(Br)−CH3\mathrm{(CH_3)_2CH-CH(Br)-CH_3}
  2. 2(CH3)2CBr−CH2−CH3\mathrm{(CH_3)_2CBr-CH_2-CH_3}
  3. 3(CH3)2CH−CH2−CH2−Br\mathrm{(CH_3)_2CH-CH_2-CH_2-Br}Official answer
  4. 4(CH3)2CH−CH2−CH2−O−COC6H5\mathrm{(CH_3)_2CH-CH_2-CH_2-O-COC_6H_5}

Official answer: option 3 · NTA final answer key

Same idea

The only question on Peroxide Effect (Anti-Markovnikov)

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

Peroxide Effect (Anti-Markovnikov): 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