Water shows concave meniscus in a narrow glass tube. This is because.

Options

A. adhesive forces is stronger than cohesive force.
B. adhesive force is weaker then cohesive forces.
C. cohesive forces and adhesive are equal
D. of absence of adhesive force.

Explanation

### Step-by-Step Solution:

1. **Understanding Meniscus**:
- A meniscus is the curve seen at the surface of a liquid in a container, such as a glass tube or test tube. It can be either concave (curving downwards) or convex (curving upwards).

2. **Identifying the Type of Meniscus**:
- Water shows a concave meniscus when placed in a narrow glass tube. This means the surface of the water curves downwards at the edges.

3. **Understanding Forces Involved**:
- There are two types of forces that affect the shape of the meniscus: adhesive forces and cohesive forces.
- **Adhesive Forces**: These are the attractive forces between dissimilar molecules, such as water molecules and glass molecules.
- **Cohesive Forces**: These are the attractive forces between similar molecules, such as water molecules attracting each other.

4. **Analyzing the Forces**:
- In the case of water in a glass tube, the adhesive forces (between water and glass) are stronger than the cohesive forces (between water molecules). This means that water molecules are more strongly attracted to the glass than to each other.

5. **Conclusion**:
- Because the adhesive forces are stronger than the cohesive forces, the water molecules are pulled up along the sides of the glass tube, resulting in a concave shape at the surface of the water. This is why water shows a concave meniscus in a narrow glass tube.

### Final Answer:
Water shows a concave meniscus in a narrow glass tube because the adhesive forces between water and glass are stronger than the cohesive forces between water molecules.

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