Question

select the correct answer. what defines the mass number of an isotope? a. the sum of the neutrons and protons b. the sum of the neutrons and electrons c. the number of neutrons d. the number of protons

Explanation:

The mass number of an isotope is defined as the sum of the number of neutrons and protons in the nucleus of an atom. Electrons do not contribute significantly to the mass of an atom.

Answer:

A. the sum of the neutrons and protons