An atom contains one proton, one electron, and one neutron. which two particles are most similar in mass?
the neutron and the electron
the proton and the electron
the proton and the neutron
the neutron and the atom

the proton and the neutron

Explanation:

An atom is made up of subatomic particles; neutrons, protons and electrons. The protons are positively charged subatomic particles found in the nucleus with a mass equal to 1.6 \times 10^{-27} kg.  The electrons are negatively charged particles of an atom found in the orbital shells in constant motion. They have a mass equal to 9.1 \times 10^{-31} kg.  The neutrons are particles found in the nucleus that have no charge and have a mass equal to 1.6 \times 10^{-27} kg. therefore protons and neutrons are similar in mass.