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Friday, 9 October

NEET UG 2021 · Chemistry · Question 71

NEET 2021 Chemistry, question 71

Question 71 of the NEET 2021 paper (code O1) is a Chemistry question from Haloalkanes and Haloarenes. Its idea, C-X Bond Enthalpy Trend, was asked only this once in NEET 2017–2026. The NTA final answer key gives option 4.

Updated 2026-10-08

Q71 · Chemistry

The correct sequence of bond enthalpy of 'C–X' bond is :

  1. 1CH3−F<CH3−Cl>CH3−Br>CH3−I\mathrm{CH_3-F < CH_3-Cl > CH_3-Br > CH_3-I}
  2. 2CH3−Cl>CH3−F>CH3−Br>CH3−I\mathrm{CH_3-Cl > CH_3-F > CH_3-Br > CH_3-I}
  3. 3CH3−F<CH3−Cl<CH3−Br<CH3−I\mathrm{CH_3-F < CH_3-Cl < CH_3-Br < CH_3-I}
  4. 4CH3−F>CH3−Cl>CH3−Br>CH3−I\mathrm{CH_3-F > CH_3-Cl > CH_3-Br > CH_3-I}Official answer

Official answer: option 4 · NTA final answer key

Same idea

The only question on C-X Bond Enthalpy Trend

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

C-X Bond Enthalpy Trend: every question and how it was framed

The chapter

Haloalkanes and Haloarenes in ten years of NEET

16 questions from 2017–2026, asked in 10 of 10 papers, about 1.5 a paper. Nucleophilic Substitution alone had 16.

Chapter analysisStudy this chapterPractise this chapter

Haloalkanes and Haloarenes: questions per paper

0241’171’181’191’202’212’223’233’241’251’26