`20 mL` of a solution containing `0.2g` of impure sample of `H_(2)O_(2)` reacts with `0.316 g` of `KMnO_(4)` (acidic). Calculate:
(a) Purity of `H_(2)O_(2)`,
(b) Volume of dry `O_(2)` evolved at `27^(@)C` and `750 mm P`.

Explanation

To solve the problem step by step, we will break it down into two parts: (a) calculating the purity of H₂O₂ and (b) calculating the volume of dry O₂ evolved.

### Part (a): Purity of H₂O₂

1. **Identify the reaction**:
The reaction between KMnO₄ and H₂O₂ in acidic medium can be represented as follows:
\[
2 \text{KMnO}_4 + 5 \text{H}_2\text{O}_2 + 6 \text{H}^+ \rightarrow 2 \text{Mn}^{2+} + 5 \text{O}_2 + 8 \text{H}_2\text{O}
...