Add proton + neutrons = Mass 37
Proton is same as your atomic mass= 17
If you go on the periodic table look up 17 and it will give u the letter.
I believe it’s B I apologize if it’s wrong
Explanation:
They are called or known as cations
Molecular mass of H2O is: 16+2*1=18
so moles of 40g of H2O is: 40/18=2.22