State Avogadro's law for matter.

(N/A) Avogadro's law states that equal volumes of all gases under the same conditions of temperature and pressure contain an equal number of molecules.
Mathematically,it is expressed as $V \propto n$ (at constant $T$ and $P$),where $V$ is the volume of the gas,$n$ is the amount of substance (number of moles),$T$ is the absolute temperature,and $P$ is the pressure.
This implies that the molar volume of all ideal gases at standard temperature and pressure $(STP)$ is the same,which is approximately $22.4 \ L$ per mole.