Question

when does nucleus of an atom tend to be radioactive?

Answer 1

the nucleus of an atom becomes radioactive when it becomes unstable or there's a large difference between the no. of protons and neutrons

Answer 2

Hyy dear..When the atomic number of an element is more than 82, it becomes radioactive because ...in their nuclei, the number of neutrons is much more than the number of protons. :-)