Two samples of lead oxide were separately reduced to metallic lead by heating in a current of hydrogen. The weight of lead from one oxide was half the weight of lead obtained from the other oxide. The data illustrates.

According to law of multiple proportion masses of element that combine with fixed mass of another element bear simple whole number ratio. So, according to this reactants must be same, but their proportions can differ. Two samples of lead oxide contain different amount of lead but yet two compounds contain same elements viz lead and oxygen, this illustrates law of multiple proportions.