A convex meniscus is formed when the cohesive force is ___ the adhesive force

Options

A. equal to
B. less than
C. greater than
D. less than or equal to

Explanation

To determine the relationship between cohesive and adhesive forces that leads to the formation of a convex meniscus, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Cohesive Forces**: These are the forces of attraction between molecules of the same substance. In liquids, these forces cause the molecules to stick together.
- **Adhesive Forces**: These are the forces of attraction between molecules of different substances, such as liquid molecules and the surface of a container (like glass).

2. **Visualize the Meniscus**:
- A meniscus is the curve seen at the surface of a liquid in a container. A convex meniscus curves upwards, while a concave meniscus curves downwards.

3. **Identify the Conditions for a Convex Meniscus**:
- A convex meniscus occurs when the adhesive forces (between the liquid and the container) are weaker than the cohesive forces (between the liquid molecules themselves). This means that the liquid molecules prefer to stick together rather than to the container.

4. **Analyze the Forces**:
- If the cohesive forces are stronger than the adhesive forces, the liquid will not spread out to wet the container's surface. Instead, it will form a convex shape, pulling itself together due to the stronger cohesive forces.

5. **Conclusion**:
- Therefore, a convex meniscus is formed when the cohesive forces are **greater than** the adhesive forces.

### Final Answer:
A convex meniscus is formed when the cohesive force is **greater than** the adhesive force.

---