Which of these is not used as a fuel in the rocket propellants

Options

A. Liquid He
B. Kerosene
C. Liquid hydrogen
D. Liquid hydrazine

Answer

To determine which of the given options is not used as a fuel in rocket propellants, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Common Rocket Fuels**:
- Rocket propellants typically consist of fuels and oxidizers. Common fuels include kerosene, alcohol, hydrazine, and liquid hydrogen.

2. **List the Given Options**:
- The options provided are:
- Liquid helium
- Kerosene
- Alcohol
- Hydrazine
- Liquid hydrogen

3. **Evaluate Each Option**:
- **Liquid Helium**: This is primarily used in cryogenics and as a coolant, not as a fuel in rocket propellants.
- **Kerosene**: This is a well-known rocket fuel, often used in combination with liquid oxygen.
- **Alcohol**: Alcohols can be used as rocket fuels, particularly in hybrid engines.
- **Hydrazine**: This is a common hypergolic fuel used in many spacecraft.
- **Liquid Hydrogen**: This is a highly efficient rocket fuel, often used in combination with liquid oxygen.

4. **Conclusion**:
- Among the options provided, **liquid helium** is not used as a fuel in rocket propellants.

### Final Answer:
Liquid helium is not used as a fuel in rocket propellants.

---