Definition of mole:
One mole of a substance is defined as the amount of substance that contains the same number of particles as in 12 g of carbon-12.
Don’t get confused by this definition. It basically means:
One mole of carbon-12 = 6.02 x 1023 particles in carbon-12 = 12 g per mole (molar mass)
Mole is just a unit of measurement which is used to calculate the number of particles that present in a substance. The symbol for mole is “mol”.
In chemistry, one mole of a substance contains 6.02 × 1023 particles in the substance. This is known as the Avogadro constant.