Question

What is meant by radioactivity? high-energy subatomic particles disintegration of the nucleus unstable atoms all of the above

Answer 1

Radioactivity is the spontaneous emission of radioactive particles like alpha,beta and gamma whenever an atom is unstable i.e. , when the number of neutrons exceeds the number of protons.

in short,  all of the above must be the answer

Answer 2

D :all of the above