Avogadro’s Constant – equal volumes of all gases measured under the same conditions of temperature and pressure contain equal numbers of molecules
Moles – the amount of a substance which contains 6×1023 atoms, ions or molecules. This number is called the Avogadro’s constant. One mole of atoms has a mass equal to the relative atomic mass (Ar) in grams. One mole of molecules has a mass equal to the relative molecular mass (Mr) in grams.
The calculation of no. of moles is moles =
The calculation of Molar Mass is Molar Mass = 
The calculation of mass is mass = number of moles x Molar Mass
The calculation of concentration is concentration =
The calculation of Volume is Volume =
The calculation of no. of moles is moles = concentration x Volume
The calculation of no. of moles is moles =
One mole of any gas at rtp = 24
The calculation of Volume = Volume x 24