"Nuclear stability is based on (choose all that apply)
the ratio of protons to neutrons
the number of valence electrons
the ratio of protons to electrons
the size of the nucleus
the amount of energy in the nucleus"

the ratio of protons to neutrons

Explanation:

Nuclear stability is based on the ratio of protons to neutrons. The nuclear space is made up of protons and neutrons that occupies the nucleus of an atom.

For every atomic nucleus, there is a specific neutron/proton ratio which ensures the stability of the nucleus.

For sodium, Na, the neutron/proton ratio for stability is 12/11.

Any nucleus with a neutron/proton combination different from its stability ratio will be unstable.

hypothesising or postulating