The mass number of a nucleus is?

A. Always less than its atomic number
B. The sum of the number of protons and neutrons present in the nucleus
C. Always more than the atomic weight
D. A fraction

Correct Answer:

Option B – The sum of the number of protons and neutrons present in the nucleus

Explanation
Mass number, is the sum of the numbers of protons and neutrons present in the nucleus of an atom.