Which of the following gases does not cause acid rain?

Options

A. Sulphur dioxide
B. Methane
C. Nitrous oxide
D. None of the above

Answer

To determine which gas does not cause acid rain, we need to analyze the gases typically involved in the formation of acid rain and identify the one that does not contribute to this process.

### Step-by-Step Solution:

1. **Understanding Acid Rain**:
- Acid rain occurs when certain gases released into the atmosphere react with water vapor. This reaction produces acids that mix with rainwater, resulting in acid rain.

2. **Identifying Common Gases that Cause Acid Rain**:
- The primary gases responsible for acid rain are:
- **Sulfur Dioxide (SO2)**: When this gas reacts with water vapor, it forms sulfuric acid (H2SO4).
- **Nitrogen Dioxide (NO2)**: This gas can react with water vapor to form nitric acid (HNO3).
- **Nitric Oxide (NO)**: Although not as common, it can also contribute to acid rain formation.

3. **Evaluating the Given Options**:
- Now, we need to evaluate the gases provided in the options to see which one does not contribute to acid rain.
- **Sulfur Dioxide (SO2)**: Causes acid rain.
- **Methane (CH4)**: This gas does not react with water vapor to form acids and therefore does not contribute to acid rain.
- **Nitrous Oxide (NO)**: This gas can also contribute to acid rain.

4. **Conclusion**:
- From the analysis, the gas that does not cause acid rain is **Methane (CH4)**.

### Final Answer:
The gas that does not cause acid rain is **Methane (CH4)**.

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