# How much sulfate dianion, SO_4^(2-) could be made from a 64*g mass of dioxygen?

You mean $\text{sulfate ion}$, $S {O}_{4}^{2 -}$.........
$64 \cdot g$ of oxygen atoms represents $\frac{64 \cdot g}{16.0 \cdot g \cdot m o {l}^{-} 1}$ $O$ $=$ $\text{4 moles of oxygen atoms.}$
And thus, with mole of sulfur atoms, i.e. $32 \cdot g$, we could make $96 \cdot g$ sulfate dianion, i.e. $S {O}_{4}^{2 -}$.
All we have done here is to take equivalent masses of sulfur ($32.06 \cdot g \cdot m o l$) and oxygen, ($15.999 \cdot g \cdot m o {l}^{-} 1$).