(Note that the factor is 
and not 
because
two (2) electrons occupy each state.)
Using data from a periodic table and assuming that each alkali atom
contributes one mobile electron to the metal, compute the
density of mobile electrons per unit volume and thus deduce the Fermi
energies for the following alkali metals: Li, Na, K, Rb, Cs. Give
your results in eV.
Hint: For these metals your results should all be on the order of a
few Volts.