To find the empirical formula of the compound, we divide the amount in moles of each of the elements by the amount in mole of the element with the smallest number of mole. In this question, the element with the smallest number of moles is oxygen with 1.36 mole. Hence, we divide the number of moles of each element by this.
H = 4.10/1.36 = 3
O = 1.36/1.36 = 1
C = 2.05/1.36 = 1.5
We then multiply through by 2 to yield the compound with the empirical formula C3H6O2
