The mole is defined as the amount of substance that contains as many particles as there are atoms in in 12 grams of carbon. [tex]n=\frac{m}{M}[/tex], n is number of moles, m is mass of atom in grams, M is the formula mass, hence neon has:
[tex]n=\frac{m}{M}= \frac{68.4 g}{20.17 g/mol} = 3.39 mol\ Ne[/tex]
