On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained.
On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?

Explanation

### Step-by-Step Solution:

1. **Understanding the Initial Reaction**:
- When a drop of barium chloride (BaCl₂) solution is added to an aqueous solution of sodium sulphite (Na₂SO₃), a chemical reaction occurs.
- The reaction can be represented as:
\[ \text{BaCl}_2 (aq) + \text{Na}_2\text{SO}_3 (aq) \rightarrow \text{BaSO}_3 (s) + 2 \text{NaCl} (aq) \]
...