State Avogadro's law.

Explanation

Avogadro.s law : Equal volumes of all gases under the same conditions of temperature and pressure contain an equal number of molecules.
Applications of Avogadro.s law :
`**` It is used to determine the atomicity of gases.
`**` It is used to determine the atomicity of gases.
`**` It is helpful in determining the molecular formula of gaseous compounds.
`**` It gives the value of molar volume of gases at STP. Molar volume of a gas at STP = 22.4 litres.
`**` It explains Gay lussac.s law effectively.