What is found in photochemical smog -

Options

A. CO
B. `NO_(2)`
C. Ozone
D. B and C both

Answer

### Step-by-Step Solution:

1. **Understanding Photochemical Smog**:
- Photochemical smog is a type of air pollution that is formed when sunlight reacts with pollutants in the atmosphere. It is commonly associated with urban areas and is often more prevalent during the summer months.

2. **Key Components of Photochemical Smog**:
- The primary components found in photochemical smog include nitrogen oxides (NOx) and ozone (O3). These substances are produced from various sources, including vehicle emissions and industrial processes.

3. **Formation Process**:
- The formation of photochemical smog occurs when sunlight catalyzes reactions between nitrogen oxides and volatile organic compounds (VOCs). This process leads to the production of ozone at ground level, which is harmful to human health and the environment.

4. **Identifying the Components**:
- Among the options provided:
- Carbon monoxide (CO) is not a primary component of photochemical smog.
- Nitrogen oxides (NOx) are indeed a significant part of photochemical smog.
- Ozone (O3) is also a key component of photochemical smog.

5. **Conclusion**:
- Therefore, the correct answer to the question "What is found in photochemical smog?" is both nitrogen oxides (B) and ozone (C). Thus, the answer is option 4: both B and C.