Calculate the molecular mass or formula mass (in amu) of each of the following substances: (a) $\mathrm{CH}_{4},$ (b) $\mathrm{NO}_{2},$ (c) $\mathrm{SO}_{3},$ (d) $\mathrm{C}_{6} \mathrm{H}_{6}$
(e) $\mathrm{NaI},$ (f) $\mathrm{K}_{2} \mathrm{SO}_{4},(\mathrm{g}) \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}$.