Learning chemistry

DEFINING ONE MOLE:-
One Mole :- One mole is the amount of a substance that contain as many particles or entities as there are atoms in exactly 12g (0.012kg) of the ¹²C isotope.

The mass of carbon-12 atom = 1.992648 X 10^-23g
and the mass of one mole of carbon = 12g
so, the number of atoms in it = 12g/mol¹²C / 1.992648 X 10^-23g/¹²C atom
                                           = 6.022 X 10²³  atoms

And this number

=6.022 X 10²³  atoms

is also known as AVOGADRO constant.