The effect of increase of temperature on surface tension and viscosity is that ………………… .

Answer

To answer the question regarding the effect of an increase in temperature on surface tension and viscosity, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Surface Tension**:
- Surface tension is defined as the force that acts at the surface of a liquid, perpendicular to the surface, along a unit length (1 cm). It is caused by the cohesive forces between liquid molecules.

2. **Effect of Temperature on Surface Tension**:
- When the temperature of a liquid increases, the kinetic energy of the molecules also increases.
- As the kinetic energy increases, the intermolecular forces of attraction between the molecules decrease.
- Consequently, the surface tension of the liquid decreases with an increase in temperature.

3. **Understanding Viscosity**:
- Viscosity is the measure of a fluid's resistance to flow. It can be thought of as the internal friction between layers of liquid as they move past each other.

4. **Effect of Temperature on Viscosity**:
- Similar to surface tension, when the temperature increases, the kinetic energy of the molecules in the liquid increases.
- This increase in kinetic energy leads to a decrease in the intermolecular forces of attraction between the layers of liquid.
- As a result, the viscosity of the liquid decreases with an increase in temperature.

5. **Conclusion**:
- In summary, with an increase in temperature, both surface tension and viscosity decrease. This is due to the increase in kinetic energy of the molecules, which reduces the intermolecular forces of attraction.

### Final Answer:
The effect of an increase in temperature on surface tension and viscosity is that both surface tension and viscosity decrease.