Question

Example 1: Three different elements have mass number
equal to 45. Their atomic numbers are 20, 21 and 22
respectively. Calculate the number of protons and neutrons for
three elements.
(UP 1994)​

Answer 1

Explanation:

(1) proton=20

Neutron=45-20=25

(2)proton=21

Neutron=45-21=24

(3)proton=22

Neutron=45-22=23