I want to know about Mol concept in detail.

one Mole is defined as the amount of substance that contains as many entities(particles like atoms, molecules, ions) as there are in exactly 12 grams of carbon-12 isotope. in other words a mole of a substance always contains same no of entities ..no matter  what the substance is.............actual no of molecules in a mole must be constant.........

HERE IS THE CALCULATION TO FIND THE AVOGADROS CONSTANT

1 mole of carbon weighs 12g, the mass of a single atom of carbon weighs 1.992648 * 10^-23 g

no of atoms in 1 mol = 12/(1.992648 * 10^-23 )      ==>6.022137*10^23 atoms or molecules per mol

A mol is the convenient unit for expressing the AMOUNT OF SUBSTANCE which may be an element or compound...............

ALL THE BEST!!!!!