a. A blackish brown coloured solid A when fused with alkali metal hydroxides in presence of air produces a dark green coloured compound B which on electrolytic.oxidation in alkaline medium gives a dark purple coloured compound C. Identify A, B and C and write the reactions involved.
(b) what happens when an acidic solution of the green compotind 'B' is allowed to stand for sometime? Give the equations involved. What is this type of reaction called?

Explanation

a. .(MnO)_(2)+4 (KOH)+(O)_(2) ldots stackrel( fuष )/(longrarr) 2 (~K)_(2) (MnO)_(4)+2 (H), (O).
Bindevie
A .-. MnO, - Manganese dioxide (pyrolusite) .f(B)-(K), (MnO)_(4)-. Potissium manganate
C .-(KMnO)_(4). - Potassiuni permanganate
b. - When an acidie solution of the green compound (B) ie .(K), (MnO)_(pm). potassium manganate is allowed to stand for sometime. it disproportionates to give permanganate
.3 (MnO)_(4)^(2-)+4 (H)^(+) rarr 2 (Mn) (O)_(4)^(2-)+(MnO)_(2)+2 (H)_(2) (O)^(prime).
This reactión is called dispropurtionation reaction.