Question

4
an atoms mass number is composed of the total number of ______ contained in an atom.
a. atoms
b. protons and neutrons
c. neutrons and electrons

Explanation:

The mass number of an atom is the sum of protons and neutrons in the nucleus. Electrons have negligible mass compared to protons and neutrons and atoms are not components that make up the mass - number calculation for a single atom.

Answer:

B. protons and neutrons