Hydrogen can be fused to form helium at

Options

A. High temperature and high pressure
B. High temperature and Low pressure
C. Low temperature and high pressure
D. Low temperature and low pressure

Answer

To solve the question "Hydrogen can be fused to form helium at?", we need to understand the conditions required for nuclear fusion.

### Step-by-Step Solution:

1. **Understanding Fusion**: Fusion is the process where two light atomic nuclei combine to form a heavier nucleus, releasing energy in the process. In this case, hydrogen nuclei (protons) fuse to form helium.

2. **Conditions for Fusion**: For fusion to occur, the positively charged nuclei must overcome their electrostatic repulsion. This requires a significant amount of energy.

3. **Temperature Requirement**: The temperature must be extremely high, typically in the range of \(10^6\) to \(10^7\) Kelvin. At these temperatures, the kinetic energy of the hydrogen nuclei is sufficient to overcome the repulsive forces between them.

4. **Pressure Requirement**: High pressure is also necessary to increase the likelihood of collisions between the hydrogen nuclei. High pressure compresses the nuclei closer together, facilitating fusion.

5. **Evaluating Options**:
- **Option 1**: High temperature and high pressure - This is correct as it meets both requirements for fusion.
- **Option 2**: High temperature and low pressure - Incorrect, as low pressure would not facilitate enough collisions.
- **Option 3**: Low temperature and high pressure - Incorrect, as low temperature does not provide enough energy for fusion.
- **Option 4**: Low temperature and low pressure - Incorrect, as neither condition is met for fusion.

6. **Conclusion**: The correct answer is **high temperature and high pressure**.

### Final Answer:
Hydrogen can be fused to form helium at **high temperature and high pressure**.

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