Question

an atom has the net charge of -1 it has 18 electrons and 20 neutrons its mass number is​

Answer 1

Answer:

mass number = proton + neutron (proton=electron)

mass number= 18+20= 38

Answer 2

Answer:

39

Explanation:

As it has 18 electrons with a -1 charge its would be 19 electrons

And we know that electron=proton

Hence, proton=19

Mass no=neutron+proton

=20+19 (20 is neutron as given in question)

=39