Principle of Avogadro's law:
Avogadro's law is a mole of a substance has a mass numerically equal to the molecular weight of the substance.1 gm mole of oxygen has a mass of 32 gm.
Avogadro's law state that the volume of a gm mol of all gases at the pressure of 760 mm Hg and the temperature of 0o C is the same and is equal to 22.4 liters.
For a certain gas, we can say that if m is its mass in kg, and M is its molecular weight, then the number of kg moles of gas n would be given by
n = m kg / M kg/kg mol
n = m / M kg moles
The Moler weight is given by V / n m3 / kg mol
V represents the total volume of the gas in m3