The correct option is Gay Lussac.
Explanation
The laws of chemical combination govern the quantitative relationships in chemical reactions. Specifically, the relationship between the volumes of gaseous reactants and products is defined by the Law of Gaseous Volumes.
Detailed Analysis:
- Gay Lussac (Correct): In 1808, Joseph Louis Gay-Lussac proposed the Law of Gaseous Volumes. This law states that when gases combine or are produced in a chemical reaction, they do so in a simple ratio by volume, provided all gases are at the same temperature and pressure. For example, 1 volume of hydrogen reacts with 1 volume of chlorine to produce 2 volumes of hydrogen chloride (Ratio 1:1:2).
- Amedeo Avogadro (Incorrect): Avogadro proposed Avogadro's Law in 1811, which states that equal volumes of all gases, at the same temperature and pressure, contain equal numbers of molecules. This provided an explanation for Gay Lussac's observations.
- Joseph Proust (Incorrect): Proust is credited with the Law of Definite Proportions, which states that a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation.
- John Dalton (Incorrect): Dalton proposed the Law of Multiple Proportions and is the father of modern Atomic Theory. His work focused primarily on the mass relationships between elements.
Key Takeaway:
Gay Lussac's Law of Gaseous Volumes establishes that gases react in simple whole-number ratios by volume, distinct from mass-based laws like Definite or Multiple Proportions.