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 (8). Compound (8) disproportionates in neutral or acidic solution to give purple compound (C). An alkaline solirtion 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.
Thinking Process

This problem based on the concept of preparation and properties of potassium permanganate.

NEETprep Answer: |tis the method of preparation of potassium permanganate (purple).
Thus,(A)=MnO2(B)=K2MnO4
(C)=KMNO4(D)=KIO3

2MnO2+4KOH+O22K2MnO4+2H2O
AB
3MnO42-+4H+2MnO4-+MnO2+2H2O
C
2MnO4-+H2O+KI2MnO2+2OH-+KIO3
AD