Carbon and oxygen combine to form two oxides, carbon monoxide and carbon dioxide in which the ratio of the weights of carbon and oxygen is respectively 12 : 16 and 12 : 32. These figures illustrate the (a) Law of multiple proportions (b) Law of reciprocal proportions (c) Law of conservation of mass (d) Law of constant proportions
The ratio of masses of oxygen which combine with a fixed mass of carbon in these compounds is 16:32 or 1:2, which is a simple whole number ratio.
