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

c. the proton and the neutron

Explanation:

the mass of the electron is 9,1094× kg

the mass of the proton is 1,6726× kg

and the mass of the neutron is 1,6749× kg

As you see the neutron is the heaviest particle, closely followed by the proton and by last is the electron.

so the neutron and the proton are the two particles with most similar masses