How do nitrogen oxides demonstrate the law of multiple proportions?

The law of multiple proportions, announced by the British scientist John Dalton in 1803, states that when two elements combine to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.1

Nitrogen oxides serve as a classic demonstration of this law. There are five distinct oxides of nitrogen, and when comparing the weights of oxygen that combine with a fixed weight of 14 grams of nitrogen, the amounts are 8, 16, 24, 32, and 40 grams. These values correspond to a simple integer ratio of 1:2:3:4:5.1

This observation provided powerful evidence for Dalton’s atomic theory, which posited that matter is composed of indivisible atoms that react in definite, fixed proportions to form compounds. By demonstrating that elements combine in predictable, simple ratios, Dalton helped transform atomic philosophy into a rigorous scientific theory.12