Correct Answer:
B. Fission splits heavy nuclei; fusion joins light nuclei.
Explanation:
The correct answer is Fission splits heavy nuclei; fusion joins light nuclei. because it accurately defines the opposite atomic mechanics powering both nuclear reactions.
- Step 1 (Fission Mechanics): Nuclear fission occurs when a large, unstable atomic nucleus (such as Uranium-235) is split into smaller, lighter nuclei by a stray neutron, releasing massive amounts of energy and radioactive waste.
- Step 2 (Fusion Mechanics): Nuclear fusion occurs when light atomic nuclei (such as isotopes of Hydrogen) are forced together under extreme heat and pressure to form a heavier nucleus (like Helium), powering stars without generating long-lived waste.
- Incorrect Options:
- Fission joins light nuclei; fusion splits heavy nuclei is incorrect because it completely reverses the true physical definitions of both processes.
- Fission requires higher temperature than fusion is incorrect because fusion requires extreme temperatures exceeding 100 million degrees Celsius to overcome electrostatic repulsion, whereas fission can occur at room temperature.
- Fission produces no radioactive waste is incorrect because fission processes inevitably split heavy atoms into highly radioactive isotopes that require strict long-term containment.