Which process creates a heavier nucleus by combining lighter ones?

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

Answer: (A)

Fusion is the process by which light nuclei combine to form a heavier nucleus. When two light nuclei fuse, the resulting nucleus has a higher binding energy per nucleon, and the mass difference between the initial and final products is released as energy. This is what powers stars, as hydrogen nuclei fuse to form helium and release enormous energy. Overcoming the electric repulsion between the positively charged nuclei is why fusion requires extreme temperatures and pressures.

Fission, on the other hand, splits a heavy nucleus into lighter ones. Transmutation changes one element into another by altering the number of protons or neutrons through nuclear reactions. Spontaneous decay is the natural transformation of an unstable nucleus into a more stable one, emitting radiation, without any fusion involved.