The smog is essentially caused by the presence of

Options

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

Answer

**Step-by-Step Solution:**

1. **Definition of Smog**: Smog is defined as a mixture of smoke and fog. It is a common form of air pollution found in many urban areas.

2. **Types of Smog**: There are two main types of smog:
- **Classical Smog**: This type is primarily composed of smoke and fog, and it is associated with the presence of sulfur oxides, particularly sulfur dioxide (SO₂).
- **Photochemical Smog**: This type occurs when sunlight reacts with unsaturated hydrocarbons (unburnt fuels) and nitrogen oxides (NOx).

3. **Components of Smog**: The key components causing smog are:
- For **Classical Smog**: Sulfur Dioxide (SO₂) and smoke.
- For **Photochemical Smog**: Nitrogen Oxides (NOx) and hydrocarbons.

4. **Conclusion**: The presence of sulfur dioxide and nitrogen oxides in the atmosphere is primarily responsible for the formation of smog. Sulfur dioxide leads to classical smog, while nitrogen oxides contribute to photochemical smog.

5. **Final Answer**: Therefore, the smog is essentially caused by the presence of sulfur dioxide and nitrogen oxides.

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