Which subatomic particle contributes least to the mass of the atom? which subatomic particle contributes least to the mass of the atom? neutron electron proton all of these contribute equally?

electron The three primary subatomic particles that make up an atom are neutrons, protons, and electrons. Both the neutrons and protons make up the nucleus of an atom and that are surrounded by a cloud of electrons. Both the neutron and proton mass about the same and their mass is about 2000 times larger than the electron. So the electron contributes the least to the mass of an atom.

My sample would be 4000 years old because on my graph, I had about 9 Virtualium left at trial 4 so I am guessing that it would be 4000 years old.