Photochemical smog mainly consists of

Options

A. ozone, peroxyacetyl nitrate and `NO_(2)`
B. smoke, peroxyacetyl nitrate and `SO_(2)`
C. hydrocarbons, `SO_(2) and CO_(2)`
D. hydrocarbons, ozone and `SO_(2)`

Answer

To answer the question "Photochemical smog mainly consists of," we can follow these steps:

### 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.

2. **Key Components**:
- The main components involved in the formation of photochemical smog include:
- **Nitrogen Oxides (NOx)**: These are produced from vehicle emissions and industrial activities.
- **Volatile Organic Compounds (VOCs)**: These are emitted from various sources, including gasoline, paints, and solvents.

3. **Role of Sunlight**:
- Sunlight, particularly ultraviolet (UV) light, plays a crucial role in the chemical reactions that lead to the formation of photochemical smog.

4. **Chemical Reactions**:
- When UV light interacts with nitrogen oxides and volatile organic compounds, a series of chemical reactions occur, resulting in the formation of secondary pollutants.

5. **Main Constituents of Photochemical Smog**:
- The primary constituents of photochemical smog include:
- **Ozone (O3)**: A harmful pollutant that is a major component of photochemical smog.
- **Peroxyacetyl Nitrate (PAN)**: A secondary pollutant formed from the reaction of VOCs and nitrogen oxides.
- **Nitrogen Dioxide (NO2)**: Another nitrogen oxide that contributes to the formation of smog.

6. **Conclusion**:
- Therefore, photochemical smog mainly consists of ozone, peroxyacetyl nitrate (PAN), and nitrogen dioxide (NO2).

### Final Answer:
Photochemical smog mainly consists of ozone, peroxyacetyl nitrate (PAN), and nitrogen dioxide (NO2).

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