Which one of the following statements is true?

Options

A. Water forms concave meniscus on account of high cohesive forces
B. Mercury forms concave meniscus on account of more adhesive force than the cohesive forces
C. Water forms convex meniscus on account of high adhesive forces than the cohesive forces
D. Mercury forms convex meniscus on account of more cohesive force than adhesive force

Answer

To determine which statement is true regarding the meniscus formed by water and mercury, we will analyze the properties of cohesive and adhesive forces in relation to these liquids.

### Step-by-Step Solution:

1. **Understanding Meniscus Formation**:
- The meniscus is the curve seen at the surface of a liquid in a container. It can be either concave (curving inward) or convex (curving outward).

2. **Identifying the Meniscus of Water**:
- Water forms a concave meniscus when placed in a glass container. This occurs because the adhesive forces between water molecules and the glass are stronger than the cohesive forces between the water molecules themselves.

3. **Identifying the Meniscus of Mercury**:
- Mercury, on the other hand, forms a convex meniscus when placed in a glass container. This is due to the cohesive forces between mercury molecules being stronger than the adhesive forces between mercury and the glass.

4. **Analyzing the Statements**:
- **Statement 1**: Water is concave - True, because water has a concave meniscus.
- **Statement 2**: Mercury is concave - False, mercury has a convex meniscus.
- **Statement 3**: Water forms concave due to high cohesive forces - False, it is due to high adhesive forces.
- **Statement 4**: Mercury forms convex due to more cohesive forces - True, as the cohesive forces in mercury are greater than the adhesive forces.

5. **Conclusion**:
- The true statement is that "Mercury forms convex due to more cohesive forces."

### Final Answer:
The true statement is: **Mercury forms convex due to more cohesive forces.**