Question

The number of neutrons in the nucleus of an atom can be determined by
(1) adding the atomic number to the mass number
(2) subtracting the atomic number from the mass number
(3) adding the mass number to the atomic mass
(4) subtracting the mass number from the atomic number

Answer 1

Option no. 2 subtracting the atomic number from the mass number

Example: Zn - 65 atomic weight or mass/mass number
                       30 atomic number
  
                 65-30 = 35 number of neutrons