Question

which is a characteristic of nuclear fusion but not nuclear fission?
○ releases large amounts of energy
○ is the energy source of stars
○ is used in electric power plants
○ requires little energy to occur

Explanation:

1. Analyze the first option: Both nuclear fusion and nuclear fission release large amounts of energy, so this is not unique to fusion.
2. Analyze the second option: Nuclear fusion is the process that powers stars (like the Sun, where hydrogen fuses into helium). Nuclear fission is not the energy source of stars, so this is a characteristic of fusion but not fission.
3. Analyze the third option: Nuclear fission is used in most nuclear power plants for electricity generation, while fusion - based power plants are still in development and not widely used for electric power production yet. So this is a characteristic of fission, not fusion.
4. Analyze the fourth option: Nuclear fusion requires extremely high temperatures and pressures (a large amount of energy input to start), while fission can occur with a relatively lower energy input (like in a nuclear reactor with a controlled chain reaction). So this statement is incorrect for fusion.

Answer:

B. is the energy source of stars