Which total mass is the smallest?
(1) the mass of 2 electrons
(2) the mass of 2 neutrons
(3) the mass of 1 electron plus the mass of 1 proton
(4) the mass of 1 neutron plus the mass of 1 electron
the mass of electrons, protons, and neutrons: electrons 9.10938291*10^-31 kg protons 1.67262178*10^-27 kg neutrons 1.6749*10^-27 kg the mass of electrons is way smaller than both, the mass of protons and neutrons therefore, 1) the mass of 2 electrons is the smallest
