Name the gas evolved in each case (formula is not acceptable).
The gas produced by the action of concentrated sulphuric acid on sodium chloride.

Explanation

To determine the gas evolved when concentrated sulfuric acid reacts with sodium chloride, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants in this case are concentrated sulfuric acid (H₂SO₄) and sodium chloride (NaCl).

2. **Write the Reaction**: When concentrated sulfuric acid reacts with sodium chloride, the following reaction occurs:
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