Describe relative atomic mass, ( A_r ), as the average mass of the isotopes of an element compared to 1/12th of the mass of an atom of ( ^{12}C )

Use the relationship amount of substance (mol) = mass (g) / molar mass (g/mol) to calculate: (a) amount of substance (b) mass (c) molar mass (d) relative atomic mass or relative molecular/formula mass (e) number of particles, using the value of the Avogadro constant