The mass number of an atom is equal to the number of
A)electrons.
B)neutrons.
C)protons.
D)protons plus neutrons.

Question

Quizplus · Accepted Answer

The mass number of an atom is defined as the total number of protons and neutrons in its nucleus. Electrons have a negligible mass compared to protons and neutrons, so they do not contribute significantly to the mass number of an atom. Therefore, the correct choice is D, which represents the total number of protons and neutrons in the atom.

The Mass Number of an Atom Is Equal to the Number