Which of these subatomic particles adds the most mass to an atom?
a. proton
b. photon
c. electron
d. It depends on what the element is.
An atom with two protons, three neutrons and two electrons would have a mass of about how many atomic mass units?
a. 2
b. 3
c. 5
d. 7
The answer for the first question is A. Proton is the subatomic particles which adds most of the mass of an atom as well as the neutron since they have the same mass. Photon, on the other hand, is not one of the subatomic particles.
