Which process is likely to occur in very heavy, unstable nuclei that split into smaller fragments?

• A. Fusion
• B. Transmutation
• C. Fission
• D. Ionization

Answer: (C)

When a nucleus is very heavy and unstable, it becomes energetically favorable for it to split into two lighter nuclei. This is fission. In fission, the heavy nucleus breaks into smaller fragments and often releases several neutrons, along with a large amount of energy. The reason this happens is that the binding energy per nucleon increases as you move from very heavy nuclei toward mid-sized ones; the resulting fragments have a higher total binding energy, so energy is released when the split occurs. That’s why heavy elements like uranium can undergo fission, sometimes spontaneously or after neutron absorption.

Fusion, in contrast, combines light nuclei to form a heavier one, not splits. Ionization involves removing or adding electrons, which changes the charge state but not the nucleus itself. Transmutation is a broad term for changing one element into another, but the description here specifically refers to a nucleus breaking apart into lighter pieces, which is characteristic of fission.