Question

The nuclei of most atoms contain multiple protons. Each proton has a positive charge. If objects that have like charges repel each other, why do the protons in the nuclei of most atoms not fly apart?
The charges of protons and neutrons cancel each other out.
Electrons outside the nucleus push on protons.
A strong nuclear force between an atom’s protons and neutrons holds together the atom’s nucleus.
Protons experience a more powerful attraction to the negatively charged particles in an atom’s nucleus.

Answer 1

A strong nuclear force between an atom’s protons and neutrons holds together the atom’s nucleus.

Explanation: The strong (nuclear) force is a very short-range but much stronger than the electromagnetic repulsion at the scale of the nucleus, so it binds protons and neutrons together. The other statements are incorrect: neutrons are neutral so they don’t “cancel” proton charge, electrons are outside the nucleus so they don’t prevent protons from repelling one another, and there is no stronger attraction of protons to negative particles inside the nucleus.