Identify the oxidation reaction in which acidified $$\mathrm{KMnO}_4$$ is required

An inorganic salt comprises of atoms of elements $$\mathrm{A}, \mathrm{B}$$ and $$\mathrm{C}$$. If the oxidation numbers of A, B and $$\mathrm{C}$$ are $$+3,+6$$ and $$-$$2 respectively, what is the possible formula of the compound?

Choose the group of ions / molecules in which none of the species undergo Disproportionation reaction.

In dilute alkaline solution $$\mathrm{MnO}_4^{-}$$ changes to