Both centrally located in an atom's nucleus, while electrons surround the nucleus in designated shells (which are commonly thought of as "orbits" as labeled in the phet simulation).

Protons and neutrons are present in nucleus and negatively charged electrons surround the nucleus.

Explanation:

There are 3 subatomic particles present in an atom. They are protons, electrons and neutrons.

A nucleus of an atom carries all the mass and it is because of the presence of neutrons and protons.

Hence, protons and neutrons are present in nucleus and negatively charged electrons surround the nucleus.

the answer is c.the valence of the atoms combine .