Photochemical smog includes the reduction of

Options

A. `SO_(2)`
B. NO
C. `Cl_(2)`
D. `NO_(2)`

Answer

To solve the question regarding photochemical smog and its relation to the reduction of certain compounds, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding Photochemical Smog**:
- Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). This reaction leads to the formation of a brown haze, which reduces visibility.

2. **Identifying Key Reactions**:
- The formation of photochemical smog involves several reactions, primarily involving nitrogen oxides. The first step is the reaction of nitrogen (N2) with oxygen (O2) to form nitric oxide (NO).
- **Reaction**:
\[ N_2 + O_2 \rightarrow 2NO \]
- In this reaction, nitrogen is oxidized from an oxidation state of 0 to +2.

3. **Further Oxidation of Nitric Oxide**:
- The nitric oxide (NO) produced can further react with oxygen to form nitrogen dioxide (NO2).
- **Reaction**:
\[ 2NO + O_2 \rightarrow 2NO_2 \]
- Here, the oxidation state of nitrogen increases from +2 in NO to +4 in NO2, indicating further oxidation.

4. **Reduction of Nitrogen Dioxide**:
- The next step involves the reduction of nitrogen dioxide (NO2) in the presence of sunlight, a process known as photolysis.
- **Reaction**:
\[ 2NO_2 \xrightarrow{sunlight} 2NO + O_2 \]
- In this reaction, the nitrogen in NO2 is reduced from an oxidation state of +4 to +2 in NO, indicating a reduction process.

5. **Conclusion**:
- From the above steps, we can conclude that the reduction process in photochemical smog specifically involves the reduction of nitrogen dioxide (NO2) to nitric oxide (NO). Thus, the correct answer to the question is that photochemical smog includes the reduction of **NO2**.

### Final Answer:
The reduction in photochemical smog includes the reduction of **NO2 (Nitrogen Dioxide)**.

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