Chemistry · 2026
JEE Main · 24 January 2026, Shift 1 · Q75
Electricity is passed through an acidic solution of Cu^2+ till all the Cu^2+ was exhausted, leading to the deposition of 300 mg of Cu metal. However,…
Electricity is passed through an acidic solution of $\displaystyle \mathrm{Cu}^{2+}$ till all the $\displaystyle \mathrm{Cu}^{2+}$ was exhausted, leading to the deposition of $\displaystyle 300$ mg of Cu metal. However, a current of $\displaystyle 600$ mA was continued to pass through the same solution for another $\displaystyle 28$ minutes by keeping the total volume of the solution fixed at $\displaystyle 200$ mL . The total volume of oxygen evolved at STP during the entire process is $\displaystyle \_\_\_\_$ mL. (Nearest integer) [Given:
$$\begin{aligned}
& \mathrm{Cu}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu}(\mathrm{~s}) \mathrm{E}_{\mathrm{red}}^{\mathrm{o}}=+0.34 \mathrm{~V} \\
& \mathrm{O}_2(\mathrm{~g})+4 \mathrm{H}^{+}+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_2 \mathrm{O} \mathrm{E}_{\mathrm{red}}^{\mathrm{o}}=+1.23 \mathrm{~V}
\end{aligned}
$$
Molar mass of $\displaystyle \mathrm{Cu}=63.54 \mathrm{~g} \mathrm{~mol}^{-1}$
Molar mass of $\displaystyle \mathrm{O}_2=32 \mathrm{~g} \mathrm{~mol}^{-1}$
Faraday Constant $\displaystyle =96500 \mathrm{C} \mathrm{mol}^{-1}$
Molar volume at $\displaystyle \mathrm{STP}=22.4 \mathrm{~L}$ ]
Official answer
From NTA’s final answer key for this paper.
111
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JEE Main 2026 Chemistry question, with the answer from NTA’s final answer key. Where our answers come from.