A white powder is found to have a percent composition $($by mass$)$ of $32\mathrm{.}0\%$ carbon, $18.\mathrm{.}7\%$ nitrogen, $6\mathrm{.}7\%$ hydrogen, and $42\mathrm{.}6\%$ oxygen.

Assuming a $100$g sample, there would be

moles of carbon,

moles of nitrogen,

moles of hydrogen, and

moles of oxygen. The empirical formula is

If the molar mass of the substance is $75$ g$/$mol$,$ the molecular formula must be