Photochemical smog does not contain

Options

A. Carbon dioxide
B. PAN (peroxy acyl nitrate)
C. Ozone
D. Nitrogen dioxide

Answer

To solve the question "Photochemical smog does not contain," we will analyze the options provided and understand the composition of photochemical smog.

### Step-by-Step Solution:

1. **Understand Photochemical Smog**:
- Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants such as nitrogen oxides and volatile organic compounds (VOCs). It is characterized by a brown haze and is most prevalent in urban areas during sunny days.

2. **Identify the Components of Photochemical Smog**:
- The primary components of photochemical smog include:
- Nitrogen Dioxide (NO2): This is a significant precursor in the formation of photochemical smog.
- Ozone (O3): Ozone is formed when nitrogen oxides react with sunlight.
- Peroxyacyl Nitrate (PAN): This is formed from the reaction of nitrogen oxides and hydrocarbons in the presence of sunlight.

3. **Analyze the Options**:
- **Option A: Carbon Dioxide (CO2)**: This is a greenhouse gas and is not a component of photochemical smog.
- **Option B: Peroxyacyl Nitrate (PAN)**: This is a component of photochemical smog.
- **Option C: Ozone (O3)**: This is also a component of photochemical smog.
- **Option D: Nitrogen Dioxide (NO2)**: This is a precursor to photochemical smog.

4. **Conclusion**:
- Based on the analysis, the component that is not found in photochemical smog is **Carbon Dioxide (CO2)**. Therefore, the correct answer is **Option A**.

### Final Answer:
Photochemical smog does not contain **Carbon Dioxide (CO2)**.

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