We are given the number of moles:
O = 1.36 mol
H = 4.10 mol
C = 2.05 mol
To get the empirical formula, first divide everything by the smallest number of moles = 1.36 mol. So that:
O = 1 mol
H = 3 mol
C = 1.5 mol
Next step is to multiply everything by a number such that all will be a whole number. In this case, multiply by 2 to get a whole number for C, so that:
O = 2 mol
H = 6 mol
C = 3 mol
Therefore the empirical formula of the compound is:
C3H6O2