Define molar mass.
The mass of one more of substance is called as molar mass.
For instance, water exists as molecules therefore, one mole of water contains 6.02 x 1023 molecules of water. Hydrogen exists H2 molecules, so one mole of hydrogen contains 6.02 x 1023 molecules. Carbon exists as atoms so 1 mole of carbon contains 6.02 x 1023 atoms.