JEE Main 2022 · 29 Jun · Shift 2 · Chemistry Q75

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ChemistrySingle correct+4 / -1Question 75 of 90

Two isomers (A) and (B) with Molar mass 184 g/mol and elemental composition C, 52.2% ; H, 4.9 % and Br 42.9% gave benzoic acid and p-bromobenzoic acid, respectively on oxidation with $\mathrm{KMnO_4}$ . Isomer 'A' is optically active and gives a pale yellow precipitate when warmed with alcoholic $\mathrm{AgNO_3}$ . Isomer 'A' and 'B' are, respectively

\mathrm{H_3C{-}CHBr{-}C_6H_5}

and 2-methylbenzyl bromide

2-Methylbenzyl bromide and 1-bromo-4-ethylbenzene

\mathrm{H_3C{-}CHBr{-}C_6H_5}

and 1-bromo-4-ethylbenzene

1-Bromo-4-ethylbenzene and

\mathrm{H_3C{-}CHBr{-}C_6H_5}

Answer and worked solution

Official answer: C

Formula $\mathrm{C_8H_9Br}$ . A is optically active and ionises easily: $\mathrm{C_6H_5CHBrCH_3}$ , oxidised to benzoic acid. B has Br on the ring para to ethyl, oxidised to p-bromobenzoic acid.

(C)

Topics:Haloarenes Optical isomerism and chirality

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JEE Main 2022 · 29 Jun · Shift 2, Chemistry question 75