Explanation

(b)
In the ground state of an atom the number of states is limited by Hund’s rule. There are [image:2_image25.emf] ways in which electron in an orbital may be arranged which do not violate Pauli’s exclusion principle.
Where, $n$=number of maximum electrons that can be filled in an orbital and $r$=number of electrons present in orbital.
But the valid ground state term is calculated by Hund’s rule of maximum multiplicity. As Hund’s rule gives the most stable electronic configuration of electrons.