How did Dalton contribute to the law of definite proportion?

Dalton's contribution to the law of definite proportions is rooted in his atomic theory, which he formulated in the early 19th century. This theory posited that all matter is made up of atoms, which are indivisible and combine in specific whole-number ratios to form compounds. The law of definite proportions states that a chemical compound always contains its component elements in fixed ratio by mass.

By developing the atomic hypothesis, Dalton provided a theoretical foundation that explained how elements combine in specific proportions to form compounds. This understanding is integral to the concept of definite proportions, as it underscores that a given compound will always have the same elemental composition, regardless of its source. Therefore, through his atomic theory, Dalton clarified the relationship between atoms and their proportions in compounds, thereby solidifying the law of definite proportions in the scientific community.

The other options do not directly relate to the law of definite proportions in the way that the atomic hypothesis does. While defining atomic theory is closely connected, it is the specific inclusion of the atomic hypothesis that directly explains how compounds maintain consistent compositional ratios.