The mass number of an atom is determined primarily by the _______ it contains.
a. number of electrons
b. number of protons
c. sum of the number of protons and electrons
d. sum of the number of protons and neutrons
e. number of charges
Answer: D
The mass number of an atom is determined primarily by the _______ it contains.
a. number of electrons
b. number of protons
c. sum of the number of protons and electrons
d. sum of the number of protons and neutrons
e. number of charges
Answer: D