Acid rain contains:

Options

A. `SO_2` and `NO_2`
B. `NO_3`
C. `O_3`
D. `CO`

Answer

**Step-by-Step Solution:**

1. **Understanding Acid Rain**: Acid rain is defined as rain 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 responsible for acid rain are sulfur dioxide (SO2) and nitrogen dioxide (NO2). These gases are released into the atmosphere through various human activities, such as burning fossil fuels.

3. **Chemical Reactions**: When sulfur dioxide (SO2) and nitrogen dioxide (NO2) are present in the atmosphere, they can react with water vapor.
- SO2 reacts with water to form sulfuric acid (H2SO4).
- NO2 reacts with water to form nitric acid (HNO3).

4. **Formation of Acid Rain**: The sulfuric acid and nitric acid formed from these reactions mix with rainwater, resulting in acid rain.

5. **Role of Carbon Dioxide**: While carbon dioxide (CO2) can also react with water to form carbonic acid (H2CO3), this acid is very weak and does not significantly contribute to the acidity of rainwater in the context of acid rain.

6. **Conclusion**: Therefore, the primary components of acid rain are sulfur dioxide (SO2) and nitrogen dioxide (NO2).

**Final Answer**: Acid rain contains sulfur dioxide (SO2) and nitrogen dioxide (NO2).

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