The proposition ‘equal volumes of different gases contain equal numbers of molecules at the same temperature Etnd pressure’ is known as

The proposition that equal volumes of different gases contain equal numbers of molecules at the same temperature and pressure is known as Avogadro’s hypothesis or Avogadro's law [1]. Formulated by Amedeo Avogadro in 1811, this principle established a fundamental relationship between the volume of a gas and the number of particles (moles or molecules) it contains. This hypothesis was crucial in distinguishing between atoms and molecules and allowed for the determination of relative molecular masses by comparing gas densities under identical conditions. In contrast, Gay-Lussac’s work primarily focused on the relationship between pressure, volume, and temperature (the law of combining volumes), while Planck’s hypothesis relates to quantum energy and Kirchhoff’s theory pertains to thermal radiation or electrical circuits. Avogadro's law remains a cornerstone of the ideal gas law.

Sources

1. [1] https://www.britannica.com/science/Avogadros-law