If a wax coated capillary tube is dipped in water, then water in it will-

Options

A. rise up
B. depress
C. sometimes rise and sometimes fail
D. rise up and come out as a fountain

Answer

To solve the problem of what happens when a wax-coated capillary tube is dipped in water, we need to understand the concepts of surface tension and capillarity.

### Step-by-Step Solution:

1. **Understanding Capillary Action**:
- Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces. This phenomenon occurs due to the adhesive forces between the liquid and the walls of the tube, as well as the cohesive forces within the liquid itself.

2. **Analyzing the Wax Coating**:
- In this case, the capillary tube is coated with wax. Wax is a hydrophobic material, which means it does not interact well with water.

3. **Determining the Angle of Contact**:
- The angle of contact (or wetting angle) is crucial in determining how the liquid behaves in the tube. For water in contact with wax, the angle of contact (θ) is greater than 90 degrees. This means that the adhesive forces between water and the wax are weaker than the cohesive forces within the water.

4. **Visualizing the Water Surface**:
- When the wax-coated capillary tube is dipped into water, the water will not rise in the tube. Instead, the surface of the water inside the tube will be depressed. This is because the water molecules are more attracted to each other (cohesion) than to the wax (adhesion).

5. **Conclusion**:
- Since the angle of contact is greater than 90 degrees, the water will not rise in the tube but will instead be depressed. Therefore, the correct answer to the question is that the water in the wax-coated capillary tube will depress.

### Final Answer:
When a wax-coated capillary tube is dipped in water, the water in it will depress.

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