Correct Answer:
B. Fission splits heavy nuclei; fusion joins light nuclei.
The fundamental difference between nuclear fission and nuclear fusion lies in their processes and the types of nuclei involved. Nuclear fission is the process where a heavy atomic nucleus, such as Uranium-235 or Plutonium-239, is split into two or more smaller nuclei, often by bombarding it with a neutron. This splitting releases an enormous amount of energy, which is harnessed in nuclear power plants and atomic weapons. Conversely, nuclear fusion is the process where two light atomic nuclei, such as isotopes of hydrogen (deuterium and tritium), combine under extreme temperatures and pressures to form a single, heavier nucleus. This process also releases a vast amount of energy and is the mechanism that powers the sun and other stars.
- Option A is incorrect because it reverses the definitions. Fission splits heavy nuclei, and fusion joins light nuclei.
- Option C is incorrect. Nuclear fusion requires significantly higher temperatures (millions of degrees Celsius) to overcome the strong electrostatic repulsion between nuclei, allowing them to fuse. Fission, while energetic, does not require temperatures nearly as high for initiation.
- Option D is incorrect. A major challenge of nuclear fission is the production of highly radioactive waste products that require safe, long-term storage. While fusion promises less long-lived radioactive waste, fission definitely produces it.