Sulphur dioxide is obtained by the action of dilute `H_2 SO_4` on :

Options

A. Copper turning
B. Sodium sulphate
C. Sodium sulphite
D. Sodium sulphide

Explanation

To determine which substance reacts with dilute H₂SO₄ to produce sulfur dioxide (SO₂), we can analyze the given options: copper turning, sodium sulfate, sodium sulfite, and sodium sulfide.

### Step-by-Step Solution:

1. **Identify the Reaction**: We need to find a substance that reacts with dilute sulfuric acid (H₂SO₄) to produce sulfur dioxide (SO₂).

2. **Examine Each Option**:
- **Copper Turning**: Copper does not react with dilute sulfuric acid to produce sulfur dioxide. Therefore, this option is not correct.
- **Sodium Sulfate (Na₂SO₄)**: Sodium sulfate is a product of reactions but does not react with dilute H₂SO₄ to produce sulfur dioxide. This option is also not correct.
- **Sodium Sulfite (Na₂SO₃)**: Sodium sulfite reacts with dilute H₂SO₄ to produce sodium sulfate and sulfur dioxide. The reaction can be represented as:
\[ Na₂SO₃ + H₂SO₄ \rightarrow Na₂SO₄ + SO₂ + H₂O \]
This option is correct as it produces sulfur dioxide.
- **Sodium Sulfide (Na₂S)**: Sodium sulfide reacts with dilute H₂SO₄ to produce sodium sulfate and sulfur dioxide as well. The reaction can be represented as:
\[ Na₂S + H₂SO₄ \rightarrow Na₂SO₄ + SO₂ + H₂O \]
This option is also correct for producing sulfur dioxide.

3. **Conclusion**: The correct answer is sodium sulfite (Na₂SO₃) and sodium sulfide (Na₂S) both react with dilute H₂SO₄ to produce sulfur dioxide (SO₂). However, since the question asks for one option, we can conclude that sodium sulfite is the primary reactant that is commonly recognized for this reaction.

### Final Answer:
Sodium sulfite (Na₂SO₃) is the substance that reacts with dilute H₂SO₄ to produce sulfur dioxide (SO₂).