(a) Write down the chemical reactions involved during the formation of photochemical smog.
(b) Which out of CO or `CO_(2)` is more dangerous pollutant ?

Explanation

### Step-by-Step Solution

#### Part (a): Chemical Reactions Involved in the Formation of Photochemical Smog

1. **Formation of Nitric Oxide (NO)**:
- Nitrogen dioxide (NO₂) is a pollutant that can break down in the presence of sunlight.
- The reaction is as follows:
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