Which one of the following statement is false ?

Options

A. Photochemical smog causes irritation in eyes
B. London smog is a mixture of smoke and fog
C. Photochemical smog results in the formation of PAN
D. London smog is oxidising in nature

Explanation

To determine which statement is false, we need to analyze each option provided:

1. **Photochemical smoke can cause irritation in eyes.**
- This statement is true. Photochemical smog, which is a type of air pollution, can indeed cause irritation in the eyes due to the presence of various pollutants, including ozone and other reactive chemicals.

2. **London smoke is a mixture of smoke and fog.**
- This statement is also true. London smog, historically associated with the city of London, is primarily a mixture of smoke (from burning coal) and fog, which occurs under certain weather conditions.

3. **Photochemical smoke results in the formation of PAN (Peroxyacetyl Nitrate).**
- This statement is true. Photochemical smog is characterized by the formation of secondary pollutants, including PAN, which is formed from the reaction of volatile organic compounds (VOCs) and nitrogen oxides in the presence of sunlight.

4. **London smoke is oxidizing in nature.**
- This statement is false. London smog is primarily reducing in nature due to the presence of sulfur dioxide and particulate matter from coal combustion, which can lead to a reduction in the oxidation state of the atmosphere.

Based on the analysis above, the false statement is:

**The fourth option: London smoke is oxidizing in nature.**

### Summary of Steps:
1. Analyze the first statement about photochemical smoke and its effects.
2. Evaluate the second statement regarding London smoke and its composition.
3. Consider the third statement about the formation of PAN from photochemical smoke.
4. Assess the fourth statement about the nature of London smoke.
5. Identify which statement is false based on the evaluations.