Percentage Composition

What is the concentration of sugar $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$ in $\mathrm{mol} {\mathrm{L}}^{-1}$ if its $20 \mathrm{g}$ are dissolved in enough water to make a final volume up to $2 \mathrm{L}$?
($0.03/0.3$)

Calculate the mass percent of different elements present in sodium sulphate $\left({\mathrm{Na}}_2{\mathrm{SO}}_4\right)$.