What is radioactive decay?

• A. The process of releasing radiation from decaying atoms.
• B. The process of turning non radioactive material radioactive.
• C. The process of splitting water into hydrogen and oxygen.
• D. The process of absorbing radiation to stop decay.

Answer: (A)

Radioactive decay is when an unstable atomic nucleus loses energy and becomes more stable, usually by emitting radiation such as alpha or beta particles or gamma rays. As the nucleus emits this radiation, it changes into a different nucleus, often a different element, and the process happens spontaneously with a probability that defines the material’s half-life.

This description matches the idea of releasing radiation from decaying atoms, which is why it’s the correct choice. Activation of non-radioactive material, splitting water via electrolysis, or absorbing radiation to stop decay are not what radioactive decay describes—activation is making a material radioactive, electrolysis is a chemical reaction, and absorbing radiation does not halt the decay process.