The mass number represents the number of
A) protons in an atom.
B) electrons in an ion.
C) neutrons in an atom.
D) protons and neutrons in an atom.
E) neutrons and electrons in an atom.

Question

Quizplus · Accepted Answer

The mass number represents the total number of protons and neutrons in an atom, which is option D. The number of electrons is not considered in the mass number calculation. And, ions have different numbers of electrons compared to neutral atoms, and, therefore, the mass number cannot be used to represent the number of electrons in an ion.

The Mass Number Represents the Number of