Final answer:
Protons and neutrons are held together in the nucleus by the strong interaction.
Step-by-step explanation:
The protons and neutrons in the nucleus are held together by the strong interaction, also known as the strong nuclear force. This force is much stronger than the electromagnetic force, which causes repulsion between positively charged protons. The strong interaction binds the protons and neutrons together and overcomes the repulsive electromagnetic forces between protons, keeping the nucleus stable.
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