Answer : The mass of 18.8 moles of helium atoms are, 75.2 grams
Explanation : Given,
Moles of helium atom = 18.8 moles
Molar mass of helium atom = 4 g/mole
Formula used :

Now put all the given values in this formula, we get the mass of helium atom.


Therefore, the mass of 18.8 moles of helium atoms are, 75.2 grams