Identify A to E. Pyrolusite on heating with KOH in the presence of air gives a dark green compound (A). The solution of (A) on treatment with `H_2SO_4` gives a purple coloured compound `(B)`, which gives the following reactions:
(a). KI on reaction with alkaline solution of (B) changes into a compound (C).
(b). The colour of the compoud (B) disappears on treatment with the acidic solution of `FeSO_4`.
(c). With conc. `H_2SO_4` compound (B) gives (D) which can compose to yield (E) and oxygen.

Explanation

To solve the question, we will identify the compounds A to E step by step based on the reactions described in the problem.

### Step 1: Identify Compound A
**Reaction:** Pyrolusite (MnO2) is heated with KOH in the presence of air.

**Chemical Equation:**
\[ 2 \text{MnO}_2 + 4 \text{KOH} + \text{O}_2 \rightarrow 2 \text{K}_2\text{MnO}_4 + 2 \text{H}_2\text{O} \]

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