Question

answer this please ​

Answer 1

I hope this helps (θ‿θ)

Answer 2

Answer:

potassium here has 20 neutrons

Explanation:

the mass number(A) is the sum of the proton(Z) or the atomic number and the neutron number(n)

A=Z+n

=> n= A - Z

n = 39 - 19

  = 20

and that's why potassium has twenty neutrons.