Question

what characteristics do atoms of argon-40, potassium-40, and calcium-40 have in common?

Answer 1

⁴⁰Ar
N(e)=18
N(p)=18
N(n)=40-18=22

⁴⁰K
N(e)=19
N(p)=19
N9n)=40-19=21

⁴⁰Ca
N(e)=20
N(p)=20
N(n)=40-20=20