According to Avogadro's hypothesis, what is true about equal volumes of gases at the same temperature and pressure?

Avogadro's hypothesis states that equal volumes of gases, when measured at the same temperature and pressure, contain an equal number of molecules, which directly translates to them containing equal numbers of moles. This principle is foundational in gas law relationships and is crucial for understanding stoichiometry in gas reactions.

When temperature and pressure are held constant, the volume is indicative of the number of gas particles present. Thus, even if the gases are different in identity, the key takeaway is that the mole count remains consistent across equal volumes. This supports various calculations in chemistry relating to reactions involving gases and allows chemists to predict the behavior of gaseous substances more accurately.

The other options do not align with Avogadro's hypothesis; for example, different gases can occupy the same volume at the same temperature and pressure without being of the same type, which negates the idea that they must consist of the same kind of gas or that they will have equal densities.