Question

Which of the given reactions is not an example of a disproportionation reaction?

• A. $2H_2O_2 → 2H_2O + O_2$
• B. $2NO_2 + H_2O → HNO_3 \+ HNO_2$
• C. $MnO4^– + 4H^+ + 3e^– → MnO_2 + 2H_2O$
• D. $3MnO_4^{2–} + 4H^+ → 2MnO_4^– + MnO_2 + 2H_2O$

Answer 1

Answer: (C)

$MnO4^– + 4H^+ + 3e^– → MnO_2 + 2H_2O$

Answer 2

$\overset{+7}{Mn}O_4^– + 4H^+ + 3e^– → \overset{+4}{Mn}O_2+ 2H_2O$
This reaction envolves the reduction of $MnO_4^–$ to $MnO_2$.

So, the correct option is (C).