The empirical formula is the simplest ratio of whole numbers of components in a compound. Molecular formula gives the actual composition of components in the compound.
Empirical formula - NO₂
Mass of one empirical unit - 14 + (16x2) = 46 g
Mass of one mole of the compound - 46 g/mol
Number of empirical units = 46 g/mol / 46 g
Number of empirical units = 1
Therefore molecular formula 1(NO₂)
Molecular formula - NO₂