JEE MAIN - Chemistry (2022 - 26th July Morning Shift - No. 4)
Which of the given reactions is not an example of disproportionation reaction?
$$2 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}$$
$$2 \mathrm{NO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{HNO}_{3}+\mathrm{HNO}_{2}$$
$$\mathrm{MnO}_{4}^{-}+4 \mathrm{H}^{+}+3 \mathrm{e}^{-} \rightarrow \mathrm{MnO}_{2}+2 \mathrm{H}_{2} \mathrm{O}$$
$$3 \mathrm{MnO}_{4}^{2-}+4 \mathrm{H}^{+} \rightarrow 2 \mathrm{MnO}_{4}^{-}+\mathrm{MnO}_{2}+2 \mathrm{H}_{2} \mathrm{O}$$
Explanation
$$
\begin{aligned}
& 2 \mathrm{H}_2 \overset{-1}{\mathrm{O}_2} \longrightarrow 2 \mathrm{H}_2 \overset{2-}{\mathrm{O}}+\overset{0}{\mathrm{O}_2}: \text { Disproportionation } \\\\
& 2 \overset{+4}{\mathrm{NO}_2}+\mathrm{H}_2 \mathrm{O} \rightarrow \overset{+5}{\mathrm{HNO}_3}+\overset{+3}{\mathrm{HNO}_2} \text { : Disproportionation } \\\\
& \mathrm{MnO}_4^{-}+4 \mathrm{H}^{+}+3 \mathrm{e}^{-} \rightarrow \mathrm{MnO}_2+2 \mathrm{H}_2 \mathrm{O}: \text { reduction } \\\\
& 3 \overset{+6}{\mathrm{MnO}_4^{2-}}+4 \mathrm{H}^{+} \rightarrow 2 \overset{+7}{\mathrm{MnO}_4^{-}}+\overset{+4}{\mathrm{MnO}_2}+2 \mathrm{H}_2 \mathrm{O}: \text { Disproportionation }
\end{aligned}
$$
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