Acid rain occurs when _____ gas present in the atmosphere dissolves in rain water to form sulphuric acid.

Options

A. Sulphur dioxide
B. Sulphur oxide
C. Carbon monoxide
D. Carbon dioxide

Answer

To answer the question about acid rain, we need to identify the gas that dissolves in rainwater to form sulfuric acid. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Acid Rain**:
- Acid rain is precipitation that has a lower pH than normal rainwater, making it acidic. This acidity is primarily due to the presence of certain gases in the atmosphere.

2. **Identifying the Gases**:
- The main gases that contribute to acid rain are sulfur dioxide (SO₂) and nitrogen oxides (NOₓ). When these gases are released into the atmosphere, they can react with water vapor.

3. **Formation of Sulfuric Acid**:
- When sulfur dioxide (SO₂) dissolves in rainwater, it undergoes a chemical reaction to form sulfurous acid (H₂SO₃). This can further oxidize to form sulfuric acid (H₂SO₄).

4. **Conclusion**:
- Therefore, the gas that is primarily responsible for the formation of sulfuric acid in acid rain is **sulfur dioxide (SO₂)**.

### Final Answer:
Acid rain occurs when **sulfur dioxide (SO₂)** gas present in the atmosphere dissolves in rainwater to form sulfuric acid.

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