Used in cryoscopic experiment

Options

A. Ne
B. Ar
C. He
D. Kr

Answer

To solve the question "Used in cryoscopic experiments," we need to identify which noble gas among the options provided is commonly utilized in cryoscopic experiments.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which noble gas is used in cryoscopic experiments. Cryoscopy involves measuring the freezing point depression of a solvent when a solute is added, which often requires the use of gases that can reach very low temperatures.

2. **Analyze the Options**: The options given are:
- Neon
- Argon
- Helium
- Triton

3. **Research Properties of Each Gas**:
- **Neon**: A noble gas that is not typically used in cryoscopic experiments.
- **Argon**: Another noble gas, but it does not have the low boiling point required for cryoscopic applications.
- **Helium**: Known for its very low boiling point of approximately 4.2 Kelvin, making it suitable for cryogenic applications.
- **Triton**: This is not a noble gas; it is a hydrogen isotope and not relevant to this question.

4. **Identify the Correct Gas**: Among the gases listed, helium is the only one that has the properties suitable for cryoscopic experiments due to its low boiling point and non-inflammable nature.

5. **Conclusion**: Therefore, the noble gas used in cryoscopic experiments is **Helium**.

### Final Answer:
The correct option is **C. Helium**.

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