Mercury is often used in clinical thermometers. Which one of the following properties of mercury is not a reason for this?

Options

A. The coefficient of the thermal expansion is large.
B. It is shiny.
C. It is a liquid at room temperature.
D. It has high density.

Answer

To solve the question regarding the properties of mercury that make it suitable for use in clinical thermometers, we will analyze each option provided and determine which property is not a reason for its use.

### Step-by-Step Solution:

1. **Understanding the Question**:
- We need to identify which property of mercury is NOT a reason for its use in clinical thermometers.

2. **Analyzing the Properties**:
- We will evaluate each property listed in the options to see if it contributes to the effectiveness of mercury in thermometers.

3. **Option A: Coefficient of Thermal Expansion**:
- Mercury has a large coefficient of thermal expansion. This means that even small changes in temperature will cause a noticeable change in the volume of mercury. This property is crucial for accurately measuring temperature changes.
- **Conclusion**: This is a valid reason for using mercury in thermometers.

4. **Option B: Shiny Appearance**:
- Mercury is shiny, which allows for easy visibility of its level in the thermometer. This property helps users read the temperature accurately.
- **Conclusion**: This is also a valid reason for using mercury in thermometers.

5. **Option C: Liquid at Room Temperature**:
- Mercury remains in a liquid state at room temperature, which is essential for a thermometer to function properly. A solid would not expand or contract in a way that could be measured effectively.
- **Conclusion**: This is a valid reason for using mercury in thermometers.

6. **Option D: High Density**:
- While mercury does have a high density (13.6 times that of water), this property does not contribute to its effectiveness in measuring temperature. High density is more relevant in applications like barometers, where measuring pressure is important.
- **Conclusion**: This is NOT a reason for using mercury in clinical thermometers.

7. **Final Answer**:
- The property of mercury that is NOT a reason for its use in clinical thermometers is **Option D: High Density**.