JEE Main 2021 — Chemistry Inorganic Chemistry

2021mcqmedium

On treating a compound with warm dil. ${H}_{2}{\mathrm{SO}}_{4}$ , gas $X$ is evolved which turns ${K}_{2}{\mathrm{Cr}}_{2}{O}_{7}$ paper acidified with dil. ${H}_{2}{\mathrm{SO}}_{4}$ to a green compound $Y$ . $X$ and $Y$ respectively are :

Official previous-year question

Held on 26 Feb 2021 · Verified 6 Jul 2026.

Options

A
$X={\mathrm{SO}}_{2},Y={\mathrm{Cr}}_{2}{O}_{3}$
B
$X={\mathrm{SO}}_{2},Y={\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$
C
$X={\mathrm{SO}}_{3},Y={\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$
D
$X={\mathrm{SO}}_{3},Y={\mathrm{Cr}}_{2}{O}_{3}$

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Solution

Sulfur dioxide gas turns acidified potassium dichromate (VI) solution from orange to green. Chromium is reduced from (VI) to (III) after reaction.

${\mathrm{SO}}_{2}+\mathrm{dil}{H}_{2}{\mathrm{SO}}_{4}\longrightarrow {\mathrm{SO}}_{3}(g)$

${\mathrm{SO}}_{3}+{K}_{2}{\mathrm{Cr}}_{2}{O}_{7}\rightarrow _{{H}_{2}{\mathrm{SO}}_{4}}^{\mathrm{dil}}{\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$

Hence, On treating a compound with warm dil. ${H}_{2}{\mathrm{SO}}_{4}$ , gas $X$ is evolved which turns ${K}_{2}{\mathrm{Cr}}_{2}{O}_{7}$ paper acidified with dil. ${H}_{2}{\mathrm{SO}}_{4}$ to a green compound $Y$ . $X$ and $Y$ respectively are ${\mathrm{SO}}_{3}$ and ${\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$ .

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Options

$X={\mathrm{SO}}_{2},Y={\mathrm{Cr}}_{2}{O}_{3}$

$X={\mathrm{SO}}_{2},Y={\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$

$X={\mathrm{SO}}_{3},Y={\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$

$X={\mathrm{SO}}_{3},Y={\mathrm{Cr}}_{2}{O}_{3}$

Solution

Sulfur dioxide gas turns acidified potassium dichromate (VI) solution from orange to green. Chromium is reduced from (VI) to (III) after reaction.

${\mathrm{SO}}_{2}+\mathrm{dil}{H}_{2}{\mathrm{SO}}_{4}\longrightarrow {\mathrm{SO}}_{3}(g)$

${\mathrm{SO}}_{3}+{K}_{2}{\mathrm{Cr}}_{2}{O}_{7}\rightarrow _{{H}_{2}{\mathrm{SO}}_{4}}^{\mathrm{dil}}{\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$

JEE Main 2021 — Chemistry Inorganic Chemistry

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Solution

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JEE Main 2021 — Chemistry Inorganic Chemistry

Options

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Solution

Your note

JEE Main Inorganic Chemistry in other years

More JEE Main Inorganic Chemistry questions

Other Chemistry topics for JEE Main

Physical Chemistry

Organic Chemistry

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