Surface tension does not vary with

Options

A. temperature
B. concentration
C. size of the surface
D. vapour pressure .

Answer

To solve the question "Surface tension does not vary with", we will analyze the options provided: temperature, concentration, size of the surface, and vapor pressure.

### Step-by-Step Solution:

1. **Understanding Surface Tension**:
- Surface tension is a property of the surface of a liquid that allows it to resist external forces due to cohesive forces between the molecules of the liquid.

2. **Analyzing Each Option**:
- **Temperature**:
- Surface tension is inversely proportional to temperature. As temperature increases, surface tension decreases. Therefore, surface tension does vary with temperature.

- **Concentration**:
- Surface tension is directly proportional to concentration. Higher concentration of a liquid leads to stronger intermolecular forces, which increases surface tension. Thus, surface tension does vary with concentration.

- **Size of the Surface**:
- Surface tension is a property of the liquid itself and does not depend on the size of the surface. It remains constant regardless of the surface area. Hence, surface tension does not vary with the size of the surface.

- **Vapor Pressure**:
- Surface tension is inversely proportional to vapor pressure. As vapor pressure increases, surface tension decreases. Therefore, surface tension does vary with vapor pressure.

3. **Conclusion**:
- Based on the analysis, surface tension does not vary with the size of the surface.

### Final Answer:
Surface tension does not vary with the size of the surface.