Vapour pressure of a pure liquid does not depend upon

Options

A. surface area
B. temperature
C. nature of the liquid
D. Both A and C

Explanation

To determine which factor does not affect the vapor pressure of a pure liquid, let's analyze the options provided:

1. **Surface Area**: The vapor pressure of a pure liquid is independent of its surface area. This is because vapor pressure is a measure of the tendency of molecules to escape from the liquid phase into the vapor phase, and this tendency does not change with the amount of liquid present or its surface area.

2. **Temperature**: Vapor pressure is highly dependent on temperature. As the temperature of a liquid increases, the kinetic energy of its molecules also increases, leading to a higher vapor pressure. Therefore, temperature is a significant factor affecting vapor pressure.

3. **Nature of Liquids**: The vapor pressure also depends on the nature of the liquid. Different liquids have different intermolecular forces, which affect how easily molecules can escape into the vapor phase. Liquids with weaker intermolecular forces will have higher vapor pressures.

4. **Both A and C**: This option suggests that both surface area and the nature of the liquid do not affect vapor pressure. However, we have established that the nature of the liquid does affect vapor pressure.

Based on this analysis, the correct answer is that the vapor pressure of a pure liquid does not depend on **surface area**.

### Step-by-Step Solution:
1. **Identify the Factors Affecting Vapor Pressure**: Understand the factors that influence vapor pressure, which include temperature and the nature of the liquid.

2. **Evaluate Each Option**:
- **Surface Area**: Determine if it affects vapor pressure. It does not.
- **Temperature**: Recognize that it does affect vapor pressure.
- **Nature of Liquids**: Acknowledge that it also affects vapor pressure.
- **Both A and C**: Since nature of the liquid does affect vapor pressure, this option is incorrect.

3. **Conclusion**: Conclude that the vapor pressure of a pure liquid does not depend on surface area.