Who is credited with proposing the Law of Definite Proportions?

The correct option is Joseph Proust.

Explanation

The Law of Definite Proportions, also known as the Law of Constant Composition, is a fundamental principle of stoichiometry. It states that a given chemical compound always contains its component elements in a fixed ratio by mass, irrespective of the source or method of preparation.

Analysis of Options:

• Joseph Proust is Correct: Joseph Proust, a French chemist, is credited with proposing the Law of Definite Proportions in 1799. He demonstrated this through experiments with cupric carbonate, showing that natural and synthetic samples contained the same percentage of copper, carbon, and oxygen.
• Antoine Lavoisier is Incorrect: Antoine Lavoisier is widely regarded as the father of modern chemistry. He is credited with establishing the Law of Conservation of Mass.
• John Dalton is Incorrect: John Dalton formulated the Atomic Theory and the Law of Multiple Proportions, which describes how elements combine in different ratios to form distinct compounds.
• Amedeo Avogadro is Incorrect: Amedeo Avogadro proposed Avogadro's Law, which relates the volume of a gas to the number of molecules present under constant temperature and pressure.

Key Takeaway:
Joseph Proust established the Law of Definite Proportions, asserting that elements combine in fixed, definite proportions by mass to form specific compounds.