Which of the following defines the mass number of an atom?
A) the number of protons in the atom
B) the number of neutrons in the atom
C) the total number of protons and neutrons in the atom
D) the total number of protons, neutrons, and electrons in the atom

Question

Quizplus · Accepted Answer

The mass number of an atom is defined as the total number of protons and neutrons in the atom. This is because protons and neutrons have a mass of approximately one atomic mass unit (amu), whereas electrons have a negligible mass (about 1/2000th the mass of a proton or neutron). Therefore, when calculating the mass of an atom, only the mass of protons and neutrons need to be considered.

Which of the Following Defines the Mass Number of an Atom