Give a chemical test to distinguish between the pairs of compounds :
Hydrogen chloride gas and Sulphur dioxide gas.

Explanation

To distinguish between hydrogen chloride gas (HCl) and sulfur dioxide gas (SO2), we can perform two separate tests:

### Step-by-Step Solution:

1. **Test for Hydrogen Chloride (HCl):**
- **Materials Needed:** A glass rod, ammonia solution (NH3).
- **Procedure:** Dip the glass rod into the ammonia solution and then expose it to the hydrogen chloride gas.
- **Observation:** If HCl is present, a white layer of ammonium chloride (NH4Cl) will form on the rod, indicating the presence of hydrogen chloride gas. This occurs because HCl reacts with ammonia to form NH4Cl, which appears as white fumes.
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