When the temperature increased the angle of contact of a liquid

Options

A. increses
B. decreases
C. remains the same
D. first increases and then decreases

Explanation

To answer the question about how the angle of contact of a liquid changes with an increase in temperature, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Angle of Contact**: The angle of contact (or contact angle) is the angle formed between the tangent to the liquid surface at the point of contact and the solid surface. It is influenced by the adhesive forces between the liquid and the solid and the cohesive forces within the liquid.

2. **Effect of Temperature on Intermolecular Forces**: When the temperature of a liquid increases, the kinetic energy of the molecules also increases. This leads to a decrease in the intermolecular forces, specifically the cohesive forces within the liquid.

3. **Cohesion vs. Adhesion**: Cohesion refers to the attractive forces between molecules of the same substance, while adhesion refers to the attractive forces between molecules of different substances (like liquid and solid). As temperature increases, the cohesive forces decrease, which affects the shape of the liquid droplet on a solid surface.

4. **Change in Contact Angle**: As the cohesive forces decrease due to the increase in temperature, the liquid tends to spread out more on the solid surface. This results in a decrease in the contact angle. A lower contact angle indicates that the liquid is wetting the surface more effectively.

5. **Conclusion**: Therefore, when the temperature of a liquid increases, the angle of contact decreases.

### Final Answer:
When the temperature increases, the angle of contact of a liquid decreases.

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