What happens when hot and concentrated sulphuric acid reacts with the following:
`NaNO_3`

Explanation

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants in this reaction are sodium nitrate (NaNO₃) and hot, concentrated sulfuric acid (H₂SO₄).

2. **Write the Reaction**: When sodium nitrate reacts with hot and concentrated sulfuric acid, the reaction can be represented as:
\[ \text{NaNO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{HNO}_3 + \text{NaHSO}_4 \]
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