When a chloride salt is heated with conc. `H_2SO_4`, `HCl` gas is evolved whereas when a bromide salt is heated with conc. `H_2SO_4`, Br gas is evolved. Why?

Explanation

To understand why different gases are evolved when heating chloride and bromide salts with concentrated sulfuric acid, we can break down the reactions step by step.

### Step 1: Reaction of Chloride Salt with Concentrated H2SO4
1. **Assume the chloride salt is Sodium Chloride (NaCl)**.
2. When NaCl is heated with concentrated sulfuric acid (H2SO4), the reaction can be represented as:
\[ \text{NaCl} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{HCl} \]
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