Example 7. The density of zinc (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s²) is 7.13g/cm³ and its atomic weight

Example 7. The density of zinc (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s²) is 7.13g/cm³ and its atomic weight is 65.4. Calculate its Fermi energy. The effective mass of free electron in zinc crystal is 7.7 ×10-³¹kg and the Avogadro's number is 6.02 × 10²³ (atom per gram) atom.