First we need to determine the number of moles of each element.
number of moles O = 3.47/16 = 0.22
number of moles N = 1.52 / 14 = 0.11
Therefore the total number of moles is 0.33
mole percent;
% mol of O = 0.67
% mol of N = 0.33
dividing by the smallest mole percentage, the empirical formula is
NO2
