There are two common oxides of sulphur, one of which contains 50% O2 by weight, the other almost contains exactly 60%. The weights of sulphur which combine with 1 g of O2 are in the ratio of

In first oxide 1 parts oxygen combines with sulphur = 5050=1Similarly for second oxide = 4060=0.67So the ratio is 1:0.67 or 3:2Thus 2 moles of O combines with 1 mole of C in compound I and 3 moles of C in compound ll i.e., in the ratio of 1 :3. Theratio being simple illustrates the law of multiple proportions