By using the formula Moles = Mass/ molar mass we can apply this.
We have 16g of helium and the molar mass of He is 4.002 Amu.
Mole = 16g/4.002Amu
Mole = 3.998 mol
Mole = 4.00 mol
There are 6.02 x 10^23 molecules in a mol so there are 4 times of 6.02 x 10^23 molecules of helium. Quite a lot huh! :)
