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JEE Main 25 July 2022, Shift 1, Chemistry Q73

Question 73 of 90 in this shift, Chemistry question 13 of 30, Section A.

A compound 'A' on reaction with 'X' and 'Y' produces the same major product but different by product 'a' and 'b'. Oxidation of 'a' gives a substance produced by ants. Compound 'A' :

\mathrm{H_2C{=}C(CH_3){-}CH_2{-}C(CH_3)_2{-}CH_3}

With X :

a+\mathrm{O{=}C(CH_3){-}CH_2{-}C(CH_3)_3}

With Y :

b+\mathrm{O{=}C(CH_3){-}CH_2{-}C(CH_3)_3}

'X' and 'Y' respectively are

The figure, in words

Reaction scheme: Compound A (2,4,4-trimethylpent-1-ene, H2C=C(CH3)-CH2-C(CH3)2-CH3) is treated with reagent X to give a + the ketone O=C(CH3)-CH2-C(CH3)3, and with reagent Y to give b + the same ketone (two branching arrows).

(1) $\mathrm{KMnO_4/H^+}$ and dil. $\mathrm{KMnO_4}$ , 273 K
(2) $\mathrm{KMnO_4}$ (dilute), 273 K and $\mathrm{KMnO_4/H^+}$
(3) $\mathrm{KMnO_4/H^+}$ and $\mathrm{O_3,\ H_2O/Zn}$
(4) $\mathrm{O_3,\ H_2O/Zn}$ and $\mathrm{KMnO_4/H^+}$ Official answer

Official answer

Option 4

NTA final key (2022 Session 2).

Chapter: Hydrocarbons
Topic: Alkenes and Alkynes
Idea tested: Reductive Ozonolysis Products

Same idea in other shifts

Asked 8× 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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.