Acid rain is caused when sulphur dioxide mixes with rain water to form ____ acid.

Options

A. Sulphuric
B. Nitric
C. Carbonic
D. Hydrochloric

Explanation

**Step-by-Step Solution:**

1. **Understanding Acid Rain**: Acid rain occurs when certain pollutants in the atmosphere mix with rainwater, resulting in precipitation that has a lower pH than normal rainwater.

2. **Identifying the Pollutant**: The primary pollutant responsible for acid rain in this context is sulfur dioxide (SO2). This gas is released into the atmosphere from various sources, including industrial processes and vehicle emissions.

3. **Chemical Reaction**: When sulfur dioxide (SO2) combines with water (H2O) in the atmosphere, it undergoes a chemical reaction. The equation for this reaction can be represented as:
\[ SO2 + H2O \rightarrow H2SO4 \]
This reaction indicates that sulfur dioxide reacts with water to form sulfuric acid (H2SO4).

4. **Conclusion**: Therefore, the correct answer to the question is that acid rain is caused when sulfur dioxide mixes with rainwater to form **sulfuric acid**.

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