JEE Main 2020 — Chemistry Physical Chemistry

2020integermedium

A $20.0\mathrm{mL}$ solution containing $0.2g$ impure ${H}_{2}{O}_{2}$ reacts completely with $0.316g$ of ${\mathrm{KMnO}}_{4}$ in acid solution. The purity of ${H}_{2}{O}_{2}$ (in $%$ ) is______ (mol. wt. of ${H}_{2}{O}_{2}=34$ ; mol. wt. of ${\mathrm{KMnO}}_{4}=158$ )

Official previous-year question

Held on 4 Sept 2020 · Verified 6 Jul 2026.

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Solution

Let mass of pure ${H}_{2}{O}_{2}$ is $x$ gram

$\begin{matrix}+7 \\ {\mathrm{MnO}}_{{4}^{-}} \\ \end{matrix} \begin{matrix} \\ + \\ \end{matrix} \begin{matrix}-1 \\ {H}_{2}{O}_{2} \\ \mathrm{vf}=2\end{matrix} \begin{matrix} \\ \rightarrow \\ \end{matrix} \begin{matrix}+2 \\ {\mathrm{Mn}}^{2+} \\ \end{matrix} \begin{matrix} \\ + \\ \end{matrix} \begin{matrix}0 \\ {O}_{2} \\ \end{matrix}$

Eq. of ${H}_{2}{O}_{2}=\mathrm{Eq}.$ of ${\mathrm{MnO}}_{{4}^{-}}$

$[\frac{x}{34}]2=[\frac{0.316}{158}]5$

$x=0.17$

So, $%$ purity of ${H}_{2}{O}_{2}$ solution $=\frac{0.17}{0.2}\times 100=85%$

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JEE Main 2020 — Chemistry Physical Chemistry

2020integermedium

Official previous-year question

Held on 4 Sept 2020 · Verified 6 Jul 2026.

Did you get this right?

Solution

Let mass of pure ${H}_{2}{O}_{2}$ is $x$ gram

Eq. of ${H}_{2}{O}_{2}=\mathrm{Eq}.$ of ${\mathrm{MnO}}_{{4}^{-}}$

$[\frac{x}{34}]2=[\frac{0.316}{158}]5$

$x=0.17$

So, $%$ purity of ${H}_{2}{O}_{2}$ solution $=\frac{0.17}{0.2}\times 100=85%$

Your note

JEE Main Physical Chemistry in other years

Keep practicing Physical Chemistry

Work through every JEE Main Physical Chemistry PYQ, year by year.

Browse all Chemistry topics

JEE Main 2020 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

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Keep practicing Physical Chemistry

JEE Main 2020 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry