Which of the following is/are properties of helium ?

Options

A. It is chemically inert.
B. It has very high thermal conductivity
C. It has extremely low boiling point
D. It has very low viscosity

Answer

To solve the question regarding the properties of helium, we will analyze each property mentioned and determine whether it is true or false based on our understanding of helium's characteristics.

### Step-by-Step Solution:

1. **Identify the Properties of Helium**:
We need to evaluate the following properties of helium:
- It is chemically inert.
- It has very high thermal conductivity.
- It has an extremely low boiling point.
- It has low viscosity.

2. **Evaluate Each Property**:
- **Property 1: Chemically Inert**:
- Helium has an atomic number of 2 and an electronic configuration of 1s². This means its outer shell is completely filled, characteristic of noble gases. Noble gases are known for their lack of reactivity due to their stable electron configuration.
- **Conclusion**: This property is **correct**.

- **Property 2: Very High Thermal Conductivity**:
- Helium is known to have low density and can transfer heat very efficiently. This results in high thermal conductivity, making it suitable for various applications, including cryogenics.
- **Conclusion**: This property is **correct**.

- **Property 3: Extremely Low Boiling Point**:
- Helium has a boiling point of about -269 °C, which is extremely low compared to other elements. The weak Van der Waals forces between helium atoms contribute to this low boiling point.
- **Conclusion**: This property is **correct**.

- **Property 4: Low Viscosity**:
- Helium has very low viscosity due to the weak cohesive forces between its atoms. This means it flows easily and has low resistance to flow.
- **Conclusion**: This property is **correct**.

3. **Final Conclusion**:
- All the properties listed for helium are correct. Therefore, the answer to the question is that all the given properties of helium are true.

### Summary of Properties of Helium:
- Chemically inert: **True**
- Very high thermal conductivity: **True**
- Extremely low boiling point: **True**
- Low viscosity: **True**