What is Radioactivity? - QS Study
QS Study

The phenomenon of spontaneous disintegration of certain atomic nuclei resulting in the emission of radioactive rays is called radioactivity.

Unstable atomic nuclei will spontaneously decompose to form nuclei with a higher stability. The decomposition process is called radioactivity. Radioactivity is a nuclear phenomenon and it is not affected by external factors such as temperature, pressure etc. This phenomenon was discovered by Henry Becqurel.