Question

What is the mass of a sample of (NH4)2SO4 that contains 8.01 x 10^24 atoms of oxygen

Answer 1

8.01E24 atoms O x (1 mol/6.022E23) = # mols O.
Then mols (NH4)2SO4 = mols O atoms x (1 mol (NH4)2SO4/4 mols O atoms) = ?
Then g (NH4)2SO4 = mols x molar mass = ?