If a neutral atom of oxygen (o) has 8 protons, 8 electrons and 7 neutrons, what is the mass number of this atom? a.8b.15c.16d.23

B. 15

Explanation:

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

Atomic number is defined as the number of protons or number of electrons that are present in an atom.

Atomic number = Number of electrons = Number of protons

Given : number of protons = 8

number of electrons = 8

number of neutrons = 7

Hence, mass number = Number of protons + Number of neutrons = 8+ 7 = 15.