Question

what makes a nucleus stable

Answer 1

Unstable Nuclei. ... In summary, it is the balance of protons and neutrons in a nucleus which determines whether a nucleus will be stable or unstable. Too many neutrons or protons upset this balance disrupting the binding energy from the strong nuclear forces making the nucleus unstable.
Hope this helps:D
Have a great rest of a brainly day!
"*AB84*"

Answer 2

In summary, basically it is the balance of protons and neutrons in a nucleus which determines whether a nucleus will be stable or unstable.