Equal number of molecules of different gases under identical
conditions of temperature and pressure occupy the same volume.
Hence, the volume occupied by one mole of an ideal gas at standard
temperature (273.15 K) and pressure (101.325 K Pa) has a fixed volume
(22.414 dm3). This indicates that the number of molecules contained in
one mole of any real gas should be a constant quantity. This number is
found to be 6.023 × 1023 and is known as Avogadro number. For more
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