Avogadro's Law states that equal volumes of all gases, at the same temperature and pressure, contain an equal number of molecules.
The volume occupied by one mole of any gas at standard temperature and pressure (STP).
A law stating that the pressure exerted by a gas is directly proportional to its absolute temperature and volume and inversely proportional to its amount in moles.
The constant in the ideal gas law with a value approximately equal to 8.31 J/(mol·K).