Which is used in high temperature thermometry ?

Options

A. Na
B. Ti
C. Ga
D. Hg

Answer

To determine which element is used in high-temperature thermometry, we can follow these steps:

### Step 1: Understand the requirements for high-temperature thermometry
High-temperature thermometry requires a substance that can remain in a liquid state over a wide range of temperatures, especially at high temperatures.

### Step 2: Identify the properties of potential candidates
Among the elements in the p-block group 13, we need to consider their physical states and temperature ranges.

### Step 3: Analyze Gallium
Gallium is a notable candidate because:
- It is a liquid at room temperature (approximately 302 K).
- It remains liquid over a wide temperature range from 302 K to 2673 K.
- It has a low vapor pressure, which is advantageous for thermometric applications.
- It is also noted for its low toxicity, making it safer to handle compared to other metals.

### Step 4: Compare with other options
- Sodium: It has a melting point of about 371 K and is not suitable for high-temperature thermometry.
- Other elements in the group (like aluminum or indium) do not have the same liquid range at high temperatures as gallium.

### Step 5: Conclusion
Based on the analysis, gallium is the element that is used in high-temperature thermometry due to its favorable properties.

### Final Answer
Gallium is used in high-temperature thermometry.

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