Find the number of free electrons per one sodium atom at T=0T=0T=0 if the Fermi level is equal to EF=3.07eVE_{F}=3.07 \mathrm{eV}EF=3.07eV and the density of sodium is 0.97 g/cm30.97 \mathrm{~g} / \mathrm{cm}^{3}0.97 g/cm3.