Which term refers to the process of two light nuclei joining to form a heavier nucleus?

• A. Fusion
• B. Fission
• C. Spontaneous decay
• D. Neutron capture

Answer: (A)

Fusion is the process where two light nuclei come together to form a heavier nucleus. When they merge, the product has a higher binding energy per nucleon, and the mass difference between the reactants and the product is released as energy. This is why fusion powers stars like our Sun, where extremely high temperatures and pressures enable light nuclei to overcome their electrostatic repulsion and fuse. It’s distinct from fission, which splits a heavy nucleus into lighter pieces; from spontaneous decay, which involves a nucleus emitting particles to become more stable; and from neutron capture, which is the addition of a neutron to a nucleus rather than the joining of two nuclei.