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

Options

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

Explanation

To understand why water shows a concave meniscus in a narrow glass tube, we need to analyze the forces at play between the water molecules and the glass.

### Step-by-Step Solution:

1. **Understanding Meniscus**: A meniscus is the curve seen at the surface of a liquid in response to its container. In the case of water in a narrow glass tube, we observe a concave meniscus, which means the water surface dips in the middle.

2. **Identifying Forces**: There are two types of forces that influence the shape of the meniscus:
- **Cohesive Forces**: These are the forces of attraction between similar molecules. In this case, they are the forces between water molecules.
- **Adhesive Forces**: These are the forces of attraction between dissimilar molecules. Here, they are the forces between water molecules and the glass of the tube.

3. **Comparing 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 attracted to the glass than to each other.

4. **Resulting Shape**: Because the adhesive forces are stronger, the water molecules are pulled up along the sides of the glass tube, creating a concave shape. This is why we see a dip in the water level at the center of the tube.

5. **Conclusion**: Therefore, the reason water shows a concave meniscus in a narrow glass tube is that the adhesive forces between the water and the glass are stronger than the cohesive forces between the water molecules.

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

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