What does radioactive decay involve?

• A. Unstable atomic nucleus loses energy by emitting ionizing particles and radiation
• B. Stable nucleus absorbs neutrons
• C. Nuclear fission to release energy
• D. Neutrons convert to protons

Answer: (A)

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation, moving toward a more stable configuration. The energy released shows up as the kinetic energy of emitted particles (like alpha or beta particles) and as gamma photons. This decay can change the nucleus itself (for example, through beta decay, a neutron can convert to a proton) or simply release energy while emitting radiation, but the defining feature is the spontaneous emission of ionizing radiation that reduces the nucleus’s energy. The other options describe different nuclear processes: absorbing neutrons is a capture reaction, fission is a splitting process that releases energy, and a general statement about neutrons converting to protons refers to a specific decay step rather than the overall decay process.