Helium is used for filling meteorological balloons and

Options

A. In gas cooled-nuclear reactor
B. As a cryogenic agent
C. Both (a) and (b)
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding the Uses of Helium:**
- Helium is a noble gas that is lighter than air, making it suitable for filling balloons. It is non-flammable and safe to use in meteorological applications.

2. **Meteorological Balloons:**
- Meteorological balloons, also known as weather balloons, are used to collect data about the atmosphere. Helium is used to fill these balloons because it is a lightweight gas that allows the balloons to ascend easily into the atmosphere.

3. **Cryogenic Properties of Helium:**
- Helium has unique cryogenic properties, meaning it can remain in a liquid state at very low temperatures. Cryogenic temperatures are typically below -150 degrees Celsius. This property makes helium an excellent coolant.

4. **Use in Gas-Cooled Nuclear Reactors:**
- In gas-cooled nuclear reactors, helium is used as a coolant due to its ability to absorb heat without becoming liquid. This helps to maintain safe operating temperatures within the reactor.

5. **Conclusion:**
- Since helium is used for both filling meteorological balloons and as a cryogenic agent in gas-cooled nuclear reactors, the correct answer to the question is "both A & B."

**Final Answer:**
Both A & B.

---