First, let's look at the two concepts individually.
Avogadro's hypothesis (also referred to as Avogadro's Law), is a gas law, experimentally derived by Amedeo Avogadro. It says that the volume of a gas is proportional to the number of moles of the gas (at constant pressure and temperature). It tells us that increasing the number of moles at a given temperature and pressure would result to an increase in volume, and a decrase in number...