Determine the number of moles of 40 g of Ne, if the molar mass of Ne is 20g.

 The molar mass of an atom is the atomic mass of that atom expressed in grams. It is also known as gram atomic mass.

$\mathrm{Given}: \mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{given} \mathrm{substance} \left(\mathrm{m}\right)= 40 \mathrm{g}$
                $\mathrm{Molar} \mathrm{mass} \mathrm{of} \mathrm{Neon} \mathrm{atom} \left(\mathrm{M}\right)= 20\mathrm{g}$
$\mathrm{Solution}$:
$\mathrm{Number} \mathrm{of} \mathrm{moles} = \frac{\mathrm{Mass} \mathrm{of} \mathrm{substance} \left(\mathrm{m}\right)}{\mathrm{Molar} \mathrm{mass} \mathrm{of} \mathrm{given} \mathrm{substance} \left(\mathrm{M}\right)}$

                                   $= \frac{40\mathrm{g}}{20\mathrm{g}}$

                                   $= 2 \mathrm{moles}$
  $\mathrm{The} \mathrm{number} \mathrm{of} \mathrm{moles} \mathrm{of} \mathrm{neon} \mathrm{atoms} \mathrm{in} 40\mathrm{g} \mathrm{of} \mathrm{sample} \mathrm{is} 2.$