Photochemical smog consists of

Options

A. `O_(3), SO_(2)` and hydrocarbons
B. `O_(3),PAN` and `NO_(2)`
C. `SO_(2),CO_(2)` and hydrocarbons
D. `SO_(2)`,PAN and smoke

Answer

**Step-by-Step Solution:**

1. **Understanding Photochemical Smog**: Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants in the atmosphere. It is characterized by a haze that often contains high levels of ozone and nitrogen oxides.

2. **Identifying Components**: The main components of photochemical smog include:
- Ozone (O3)
- Nitrogen oxides (NOx), which include nitrogen dioxide (NO2)
- Peroxyacetyl nitrate (PAN), which is a secondary pollutant formed from the reaction of hydrocarbons and nitrogen oxides in the presence of sunlight.

3. **Evaluating Options**:
- **Option 1**: Ozone, Sulphur dioxide, and hydrocarbons.
- This option is incorrect because while ozone is a component, sulphur dioxide is not a primary component of photochemical smog.
- **Option 2**: Ozone, PAN, and NO2.
- This option is correct as it includes ozone, PAN, and nitrogen dioxide, which are all significant components of photochemical smog.
- **Option 3**: Sulphur dioxide, carbon dioxide, and hydrocarbons.
- This option is incorrect because sulphur dioxide and carbon dioxide are not major contributors to photochemical smog.
- **Option 4**: Sulphur dioxide, PAN, and smoke.
- This option is incorrect because it includes sulphur dioxide, which is not a primary component of photochemical smog.

4. **Conclusion**: Based on the analysis, the correct answer is **Option 2: Ozone, PAN, and NO2**.

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