JEE Main 2020 — Chemistry Physical Chemistry

2020numerical valuehard

$108 g$ of silver (molar mass $108 g{mol}^{-1}$ ) is deposited at cathode from ${AgNO}_{3}(aq)$ solution by a certain quantity of electricity. The volume (in $L$ ) of oxygen gas produced at $273 K$ and $1$ bar pressure from water by the same quantity of electricity is ________

Official previous-year question

Held on 9 Jan 2020 · Verified 6 Jul 2026.

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Solution

${({n}_{Ag})}_{deposit}=\frac{108}{108}=1 mole$

${\mathrm{Ag}}^{+}+{e}^{-}\longrightarrow \mathrm{Ag}$

$1F$ charge is required to deposit $1\mathrm{mole}$ of $\mathrm{Ag}$

${H}_{2}O$ $\longrightarrow \frac{1}{2}{O}_{2}+2{H}^{+}+2{e}^{-}$

$2F$ charge is required to deposit $\frac{1}{2}mole$

$1F$ charge will deposit $\frac{1}{4}mole$ of ${O}_{2}$ gas.

${V}_{{O}_{2}}=\frac{nRT}{P}$

$=\frac{1}{4}\times \frac{0.0821\times 273}{1}=\frac{1}{4}\times 22.4$

${V}_{{O}_{2}}=5.6 L$

Faraday's second law of electrolysis states that, when the same quantity of electricity is passed through several electrolytes, the mass of the substances deposited are proportional to their respective equivalent weight.

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JEE Main Physical Chemistry in other years

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

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JEE Main 2020 — Chemistry Physical Chemistry

2020numerical valuehard

Official previous-year question

Held on 9 Jan 2020 · Verified 6 Jul 2026.

Did you get this right?

Solution

${({n}_{Ag})}_{deposit}=\frac{108}{108}=1 mole$

${\mathrm{Ag}}^{+}+{e}^{-}\longrightarrow \mathrm{Ag}$

$1F$ charge is required to deposit $1\mathrm{mole}$ of $\mathrm{Ag}$

${H}_{2}O$ $\longrightarrow \frac{1}{2}{O}_{2}+2{H}^{+}+2{e}^{-}$

$2F$ charge is required to deposit $\frac{1}{2}mole$

$1F$ charge will deposit $\frac{1}{4}mole$ of ${O}_{2}$ gas.

${V}_{{O}_{2}}=\frac{nRT}{P}$

$=\frac{1}{4}\times \frac{0.0821\times 273}{1}=\frac{1}{4}\times 22.4$

${V}_{{O}_{2}}=5.6 L$

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

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Answer

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

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Keep practicing Physical Chemistry

JEE Main 2020 — Chemistry Physical Chemistry

Did you get this right?

Answer

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