When an oxide of manganese (A) is fused with KOH in the presence of an oxidising agent and dissolved in water, it gives a dark green solution of compound (B). Compound (B) disproportionates in neutral or acidic solution to give purple compound (C ). An alkaline solution of compound (C ) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds (A) to (D) and also explain the reactions involved.

Explanation

`A=MnO_(2), B=K_(2)MnO_(4), C=KMnO_(4), D=KIO_(3)`
Reactions :
(i) `2MnO_(2)(A)+4KOH+O_(2)rarr 2K_(2)MnO_(4)(B)+2H_(2)O`
(ii) `3MnO_(4)^(2-)+4H^(+)rarr 2MnO_(4)^(-)(C )+MnO_(2)+2H_(2)O`
(iii) `2MnO_(4)^(-)+H_(2)O+KI rarr 2MnO_(2)(A)+KIO_(3)(D)+2OH^(-)`