As the temperature of water increases, its viscosity

Options

A. remains unchanged
B. decreases
C. increases
D. increases or decreases depending on the external pressure

Explanation

To solve the question regarding the relationship between the temperature of water and its viscosity, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Viscosity**:
- Viscosity is a measure of a fluid's resistance to flow. It indicates how thick or sticky a fluid is.

2. **Relationship Between Viscosity and Temperature**:
- It is known from fluid mechanics that the viscosity of liquids generally decreases with an increase in temperature. This is because higher temperatures provide more energy to the molecules, allowing them to move more freely.

3. **Mathematical Expression**:
- The relationship can be expressed as:
\[ \eta \propto \frac{1}{\sqrt{T}} \]
- Here, \(\eta\) represents viscosity and \(T\) represents temperature. This indicates that viscosity is inversely proportional to the square root of temperature.

4. **Conclusion**:
- As the temperature of water increases, the viscosity decreases. Therefore, the correct statement is that the viscosity of water decreases with an increase in temperature.

### Final Answer:
As the temperature of water increases, its viscosity decreases.

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