The energy state of an atom is an energy level.

No , Fermi Surface is not always spherical . Because the kinetic energy is not same.

the highest energy level which an electron can occupy the valance band at 0k is called fermi energy level

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The Fermi Energy is the highest energy level that a group of fermions, at absolute zero, can occupy. Wolfgang Pauli was able to show that no fermion can occupy the same quantum state as another one; so any group of fermions must have one at the lowest energy level, one at the next energy leve, etc. The highest level that such a group of fermions can occupy is called the Fermi Energy.