The smog is essentially caused by the presence of

Options

A. `O_(2) "and" O_(3)`
B. `O_(2) "and " N_(2)`
C. Oxidise of sulphur and nitrogen
D. `O_(3) "and" N_(2)`

Answer

**Step-by-Step Solution:**

1. **Understanding Smog**: Smog is a type of air pollution that is a mixture of smoke and fog. It is typically characterized by its brownish color and is often associated with urban areas.

2. **Components of Smog**: The primary components that contribute to the formation of smog include sulfur dioxide (SO2) and nitrogen oxides (NOx), particularly nitrogen dioxide (NO2).

3. **Role of Sunlight**: The presence of sunlight plays a crucial role in the formation of smog. This process is referred to as photolysis, where sunlight breaks down certain pollutants.

4. **Chemical Reactions**:
- Nitrogen dioxide (NO2) reacts with sunlight, leading to the formation of nascent oxygen (O) and nitrogen monoxide (NO).
- The nascent oxygen then reacts with oxygen (O2) present in the atmosphere to form ozone (O3).
- Ozone can further react with nitrogen oxides and hydrocarbons, leading to the formation of secondary pollutants such as peroxyacetyl nitrate (PAN).

5. **Environmental Conditions**: Smog formation is more prevalent in cold and humid climates, where the conditions are favorable for the accumulation of pollutants.

6. **Conclusion**: Therefore, the smog is essentially caused by the presence of sulfur dioxide (SO2) and nitrogen oxides (NOx), along with the influence of sunlight.

**Final Answer**: The smog is essentially caused by the presence of sulfur dioxide (SO2) and nitrogen oxides (NOx).

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