Answer:
as no. of protons is equals to the no. of electrons so, it is a neutral atom.
but, as Atomic No. = Mass No. - No. of neutrons
Atomic No. = No. of protons = 18
so, Mass No. = Atomic No. + No. of Neutrons= 18 + 20 = 38
so, correct option is C.
Explanation:
Answer:

Explanation:
For this problem, you will have to convert moles to atoms. Use Avogadro's number.

B. As3 because potassium atoms do this to form ions with the same electron configuration as the noble gas argon