When `MnO_(2)`, is fused with KOH in the presence of `KNO_(3)` as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionates in acidic solution to give purple compound (B). An alkaline solution of compound (B) oxidises Kl to compound (C)whereas an acidified solution of compound (B) oxidises KI to (D), Identity (A), (B), (C), and (D).

Explanation

`2MnO_(2)+4KOH+O_(2)tounderset((A))(2K_(2)MnO_(4))+2H_(2)O`
`underset("(Green)")underset("Manganate")(MnO_(4)^(2-))+H_(2)O+KItounderset("Purple Compound")(2MnO_(4)^(-))+MnO_(2)+2H_(2)O`
`2MnO_(4)^(-)+H_(2)O+KIto2MnO_(2)+2OH^( -)+underset((C) )(KIO_(3))`
`2KMnO_(4)+3H_(2)SO_(4)+10KItoK_(2)SO_(4)+2MnSO_(4)+8H_(2)O+5I_(2)`