Which of the following statements is not true about classical smog?

Options

A. Its main components are produced by the action of sunlight on eissions of automobiles and factories.
B. Produced in cold and humid climate
C. It contains compounds of reducing nature.
D. It contains smoke, fog and sulphur dioxide

Explanation

To determine which statement is not true about classical smog, let's analyze the characteristics of classical smog and evaluate the provided statements.

### Step 1: Understand Classical Smog
Classical smog is typically associated with cold and humid climates. It is characterized by the presence of smoke, fog, and sulfur dioxide (SO₂). This type of smog is often seen in industrial areas where coal is burned, especially during the winter months.

### Step 2: Analyze Each Statement
1. **Statement 1**: "Its main components are produced by the action of sunlight on emissions from automobiles and factories."
- This statement describes photochemical smog, not classical smog. Photochemical smog occurs when sunlight reacts with pollutants like nitrogen oxides and volatile organic compounds, leading to the formation of ozone and other secondary pollutants. Therefore, this statement is **not true** about classical smog.

2. **Statement 2**: "Produced in cold and humid climate."
- This statement is true. Classical smog forms in cold and humid conditions, particularly in the early morning.

3. **Statement 3**: "It contains compounds of reducing nature."
- This statement is also true. Classical smog contains reducing agents like sulfur dioxide and particulate matter.

4. **Statement 4**: "It contains smoke, fog, and sulfur dioxide."
- This statement is true as well. Classical smog is characterized by the presence of smoke, fog, and sulfur dioxide.

### Conclusion
Based on the analysis, the statement that is not true about classical smog is **Statement 1**.

### Final Answer
The statement that is not true about classical smog is: **"Its main components are produced by the action of sunlight on emissions from automobiles and factories."**