JAMB Chemistry 2018 Paper

Concept:This illustrates the law of multiple proportions, which relates to when two elements form more than one compound.Explanation:Element X combines with chlorine to give three different compounds: $\mathrm{XCl}_4$, $\mathrm{XCl}_3$, and $\mathrm{XCl}_2$.In each compound, the mass of chlorine that combines with a fixed mass of X is in a simple whole-number ratio.The ratios of chlorine atoms are $4 : 3 : 2$, which is a simple multiple ratio.Therefore, the observation fits the law of multiple proportions.Answer:A. law of multiple proportions.