Environmental Science Practice Exam 2026 – Complete Prep for Dual Enrollment

Radioactivity is the process by which unstable atomic nuclei spontaneously transform to more stable configurations, releasing energy as radiation. This energy release comes from inside the nucleus as it moves toward stability, and it can take the form of alpha particles, beta particles, or gamma photons. Saying the nucleus loses energy by emitting radiation captures this nuclear decay behavior, which is why it’s the best description.

The other statements are narrower or describe a different scenario. Emitting only gamma radiation doesn’t cover all ways nuclei can decay (alpha and beta emissions are common too). Describing energy release from chemical bonds is a chemical, not nuclear, process. Absorption of radiation by the nucleus would be gaining energy, not the spontaneous decay that defines radioactivity.