The purple colour of `KMnO_4`, will not be discharged by which of the following reagents? 1)M n S O 4 / Z n 2 + 2)H 2 O 2 / H + 3)K N O 3 4)K 2 S / H +

Options

A. `MnSO_4 // Zn^(2+)`
B. `H_2 O_2 //H^(+)`
C. ` KNO_3`
D. `K_2 S//H^(+)`

Answer

C

Explanation

`Mn^(2+) ` ( in presence of ` Zn^(2+)`) `H_2 O_2` and `S^(2-)` are reducing agents and reduce `Mn^(7+)` by which colour is discharged , while in `KNO_3` nitrogen is in +5 oxidation state and cannot be further oxidized and hence cannot act as reducting agent .