Question

An element has an atomic number of 18 and an atomic mass of 40. The number of neutrons in the nucleus of an atom of this element is????

Answer 1

Answer: 22 neutrons

Explanation: 40 is the mass number = atomic mass = total number of protons and neutrons in atomic nucleus

18 is the number of protons in the nucleus of this atom

Then 40 - 18 = 22 neutrons

and this is Argon