The gas that is most convenient to use in gas thermometers

Options

A. `He`
B. `Xe`
C. `N_2`
D. `CO_2`

Answer

To determine the gas that is most convenient to use in gas thermometers, we will analyze the given options and their properties.

### Step 1: Identify the options
The options provided are:
1. Helium
2. Xenon
3. Nitrogen (N2)
4. Carbon Dioxide (CO2)

### Step 2: Consider the properties of the gases
- **Helium**: A noble gas that is non-reactive and has a low boiling point. It remains in a gaseous state over a wide range of temperatures.
- **Xenon**: Another noble gas, but it is heavier and less commonly used in thermometers due to its reactivity compared to helium.
- **Nitrogen (N2)**: A diatomic molecule that is relatively inert but can react under certain conditions, which may not make it ideal for precise measurements in thermometers.
- **Carbon Dioxide (CO2)**: This gas can react with water and is also subject to phase changes (solid, liquid, gas) under varying pressure and temperature, making it less suitable for gas thermometers.

### Step 3: Evaluate the best option
Among the gases listed, **helium** stands out as the most suitable option for gas thermometers. Its non-reactive nature and stable behavior across a wide temperature range make it the most convenient gas to use.

### Conclusion
The gas that is most convenient to use in gas thermometers is **helium**.

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