Describe the interaction that is responsible for keeping protons and neutrons together in a stable nucleus.

The interaction responsible for keeping protons and neutrons together in a stable nucleus is the strong interaction. The strong interaction has a very short range of less than/up to 5fm. The strong interaction is responsible for the strong nuclear force between nucleons, the protons and neutrons. Hence, protons and neutrons are attracted together up to 5fm. Beyond 5fm, the attraction is negligible. However, any distance below 1fm, the strong nuclear force between the nucleons becomes repulsive. The strong nuclear force is mediated by gluons or pions, and it only affects hadrons, baryons and mesons.