Question

Am element has 18 electrons ,20 neutrons and a charge of -2.what is the mass number?..a.38 b.40 c.32 d.39​

Answer 1

Surely you must have a Periodic Table beside you....?

a=38

Step-by-step explanation:

You gots Z=18, the atomic number, where Z is the number of nuclear protons. The number of protons defines the element....and thus we got calcium....

....and with 20 neutrons we got the 38Ca isotope....the which is rather short-lived...