JEE Main 2021 · ChemistryMultiple choiceSingle correctMediumApplication

JEE Main 25 February 2021, Shift 1, Chemistry Q46

Question 46 of 90 in this shift, Chemistry question 16 of 30, Section A.

Which one of the following reactions will not form acetaldehyde ?

(1) $\mathrm{CH_2{=}CH_2 + O_2}$ $\xrightarrow[\mathrm{H_2O}]{\mathrm{Pd(II)/Cu(II)}}$
(2) $\mathrm{CH_3CH_2OH}$ $\xrightarrow{\mathrm{CrO_3-H_2SO_4}}$ Official answer
(3) $\mathrm{CH_3CN}$ $\xrightarrow[\mathrm{ii)\ H_2O}]{\mathrm{i)\ DIBAL\text{-}H}}$
(4) $\mathrm{CH_3CH_2OH}$ $\xrightarrow[573\ \mathrm{K}]{\mathrm{Cu}}$

Official answer

Option 2

NTA final key.

Chapter: Aldehydes, Ketones and Carboxylic Acids
Topic: Carboxylic Acids and Derivatives
Idea tested: DIBAL-H Selective Reduction

Same idea in other shifts

Asked 4× in all

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.