What is Hund rule?
Hund's Rule. Hund's rule: every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
What is first excited state?
Well, the ground state is the 1s1 configuration… the first excited state (search " H I ") is the 1s02p1 configuration. https://www.physics.nist.gov/ The energy for this hydrogen-like atom is given by: En=−Z2⋅13.61 eVn2.