# When a salt is heated with dil $H_2SO_4$ and $KMnO_4$ solution, the pink colour of $KMnO_4$ is discharged, the mixture contains:

(a) Sulphite
(b) Carbonate
(c) Nitrate
(d) Bicarbonate

$SO_3^{2-}$ reduces $KMnO_4$ and colour of $KMnO_4$ is discharged.
$5SO_3^{2-} + 2MnO^-_4 + 6H^+ \longrightarrow 2Mn^{2+} + 5SO_4^{2-} + 3H_2O$