Concept Of Mole

Mole can be define as,

The atomic mass, molecular mass, ionic mass or formula mass of a substance expressed in grams is called mole of that substance.

OR

The amount of a substance, which contains 6.02 x 10²³ atoms, molecules, ions or formula units is called mole of that substance.

OR

The amount, which contains Avogadro's number of units i.e., atoms, molecules, ions, formula units or what is under consideration is called mole.