JEE Main 2021 — Chemistry Physical Chemistry

2021integerhard

When $5.1g$ of solid ${\mathrm{NH}}_{4}\mathrm{HS}$ is introduced into a two litre evacuated flask at $27^{\circ}C,20%$ of the solid decomposes into gaseous ammonia and hydrogen sulphide. The ${K}_{p}$ for the reaction at $27^{\circ}C$ is $x\times {10}^{-2}$ . The value of $x$ is (Integer answer)

[Given $1R=0.082L\mathrm{atm}{K}^{-1}{\mathrm{mol}}^{-1}]$

Official previous-year question

Held on 27 Aug 2021 · Verified 6 Jul 2026.

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Solution

Moles of ${\mathrm{NH}}_{4}\mathrm{HS}$ initially taken $=\frac{5.1g}{51g/\mathrm{mol}}=0.1\mathrm{mol}$

volume of vessel $=2L$

${\mathrm{NH}}_{4}{\mathrm{HS}}_{(s)}\rightleftharpoons {\mathrm{NH}}_{3(g)}+{H}_{2}{S}_{(g)}$

$t=00.1\mathrm{mol}$

$\begin{matrix}t=\infty & 0.1(1-0.2) & 0.1\times 0.2 & 0.1\times 0.2\end{matrix}$

Partial pressure of each gaseous component

$P=\frac{nRT}{V}=\frac{0.1\times 0.2\times 0.082\times 300}{2}$

$=0.246\mathrm{atm}$

$\Rightarrow {k}_{P}={P}_{{\mathrm{NH}}_{3}}\times {P}_{{H}_{2}S}=(0.246{)}^{2}=0.060516$

$=6.05\times {10}^{-2}$

$\Rightarrow 6$

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JEE Main 2021 — Chemistry Physical Chemistry

2021integerhard

[Given $1R=0.082L\mathrm{atm}{K}^{-1}{\mathrm{mol}}^{-1}]$

Official previous-year question

Held on 27 Aug 2021 · Verified 6 Jul 2026.

Did you get this right?

Solution

Moles of ${\mathrm{NH}}_{4}\mathrm{HS}$ initially taken $=\frac{5.1g}{51g/\mathrm{mol}}=0.1\mathrm{mol}$

volume of vessel $=2L$

${\mathrm{NH}}_{4}{\mathrm{HS}}_{(s)}\rightleftharpoons {\mathrm{NH}}_{3(g)}+{H}_{2}{S}_{(g)}$

$t=00.1\mathrm{mol}$

$\begin{matrix}t=\infty & 0.1(1-0.2) & 0.1\times 0.2 & 0.1\times 0.2\end{matrix}$

Partial pressure of each gaseous component

$P=\frac{nRT}{V}=\frac{0.1\times 0.2\times 0.082\times 300}{2}$

$=0.246\mathrm{atm}$

$\Rightarrow {k}_{P}={P}_{{\mathrm{NH}}_{3}}\times {P}_{{H}_{2}S}=(0.246{)}^{2}=0.060516$

$=6.05\times {10}^{-2}$

$\Rightarrow 6$

Your note

JEE Main Physical Chemistry in other years

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JEE Main 2021 — Chemistry Physical Chemistry

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Solution

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JEE Main Physical Chemistry in other years

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JEE Main 2021 — Chemistry Physical Chemistry

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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

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