The splitting of a heavy nucleus into lighter, more stable nuclei is called

• A. Fission
• B. Fusion
• C. Transmutation
• D. Radioactive decay

Answer: (A)

Nuclear fission is the process where a heavy nucleus splits into lighter, more stable nuclei, releasing energy in the process. This happens because the binding energy per nucleon increases when moving from very heavy nuclei to lighter ones, so the resulting fragments are more tightly bound on average and the excess energy is released. Energy from fission powers nuclear reactors and can drive explosive release through chain reactions when neutrons produced by fission trigger further fissions.

Fusion would be the opposite: light nuclei combining to form heavier ones. Transmutation refers to changing one element into another through nuclear reactions, which is broader than just splitting. Radioactive decay is the spontaneous breakdown of an unstable nucleus into a different one, typically emitting radiation, not necessarily splitting into two lighter nuclei.