All the Mass of an Atom is Considered to Be

Question

All the mass of an atom is considered to be in the:
A) protons only.
B) protons and neutrons.
C) electrons only.
D) protons, neutrons, and electrons.

Accepted Answer

The mass of an atom is primarily located in its nucleus, which contains protons and neutrons. Electrons have a very small mass relative to protons and neutrons, so they contribute very little to the overall mass of an atom. Therefore, the best choice is B: protons and neutrons.