Question

Atomic mass of an element is equal to the sum of number of

(a) electrons and protons only

(b) protons and neutrons only

(c) electrons and neutrons only

(d) electrons, protons and neutrons

Answer 1

(b) protons and neutrons only

Atomic mass of an element is equal to the sum of number of protons and neutrons only e.g. carbon atom.

Number of protons = 6 

Number of neutrons = 6

Atomic mass of carbon = 6 + 6 = 12