Which of the following reactions are disproportionation reactions -
(i) `Cu^(+)rarr Cu^(2+)+Cu`
(ii) `3MnO_(4)^(2-)+4H^(+)rarr 2MnO_(4)^(-)+MnO_(2)+2H_(2)O`
(iii) `2KMnO_(4)rarr K_(2)MnO_(4)+MnO_(2)`
(iv) `2MnO_(4)^(-)+3Mn^(2+)+2H_(2)O rarr 5MnO_(2)+4H^(+)`

Options

A. (i), (ii)
B. (i), (ii), (iii)
C. (ii), (iii), (iv)
D. (i), (iv)

Answer

A

Explanation

In (i), `Cu^(+)` is oxidised to `Cu^(2+)` and at the same time it is reduced to Cu.
In (ii), `overset(VI)(Mn)O_(4)^(2-)` is oxidised to `overset(VII)(Mn)O_(4)^(-)` and at the same time it is reduced to `MnO_(2)`.