Molecular forces exist between the molecules of a liquid in a container. The molecules on the surface have unequal force leading to a tension on the surface. If this is not compensated by a force, the equilibrium of the liquid will be a difficult task. This leads to an excess pressure on the surface. The nature of the meniscus can inform us of the direction of the excess pressure. The angle of contact of the liquid decided by the forces between the molecules, air and container can make the angle of contact.
The direction of the excess pressure in the meniscus of a liquid of angle of contact `2pi//3` is

Options

A. upward
B. downward
C. horizontal
D. cannot be determined

Explanation

To determine the direction of excess pressure in the meniscus of a liquid at an angle of contact of \( \frac{2\pi}{3} \) (or 120 degrees), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Meniscus Formation**:
- The meniscus is the curve at the surface of a liquid in a container. The shape of the meniscus is influenced by the intermolecular forces between the liquid molecules, the container, and the air above.

2. **Identifying the Angle of Contact**:
- The angle of contact (or wetting angle) is given as \( \frac{2\pi}{3} \) radians, which is equivalent to 120 degrees. This angle indicates how the liquid interacts with the container's surface.

3. **Determining the Nature of the Meniscus**:
- When the angle of contact is greater than 90 degrees (as in this case, where it is 120 degrees), the meniscus formed is concave downwards. This means that the liquid tends to pull away from the container's surface.

4. **Excess Pressure Concept**:
- The excess pressure in a liquid is related to the curvature of the liquid surface. For a concave meniscus, the pressure inside the liquid is greater than the pressure outside.

5. **Direction of Excess Pressure**:
- In a concave meniscus, the excess pressure acts towards the center of the curvature of the liquid surface. Therefore, the direction of the excess pressure is directed upwards.

6. **Conclusion**:
- Since the angle of contact is \( \frac{2\pi}{3} \), which leads to a concave meniscus, the direction of the excess pressure in the meniscus is upwards.

### Final Answer:
The direction of the excess pressure in the meniscus of a liquid at an angle of contact of \( \frac{2\pi}{3} \) is **upwards**.