Which subatomic particle has no charge and is found in the nucleus of an atom?

• A. A subatomic particle with a negative charge
• B. A subatomic particle that has a positive charge located outside the nucleus
• C. A massless particle that mediates forces
• D. A subatomic particle that has no charge and is found in the nucleus of an atom

Answer: (D)

A neutral particle inside the nucleus is the neutron. Neutrons have no electric charge and sit in the nucleus alongside protons, contributing to the nucleus’s mass and helping hold it together through the strong nuclear force. The other descriptions point to different particles: a negatively charged particle is an electron, which orbits outside the nucleus; a positively charged particle located outside the nucleus would be incorrect for the nucleus itself since protons are positive and reside in the nucleus; a massless particle that mediates forces refers to a photon, which carries electromagnetic force and is not a constituent of the nucleus. So, the neutral, nucleus-located particle is the neutron.