Question

What does Hund's rule state?

An orbital can contain two electrons only if the electrons have opposite spins.

An orbital can contain two electrons only if all other orbitals at that sublevel are empty.

An orbital can contain two electrons only if the electrons have different energy levels.

An orbital can contain two electrons only if all other orbitals in that sublevel contain at least one electron.

Answer 1

The 39 clues reference in your username?

Answer 2

Hunds' Rule basically states that every orbital in an energy sublevel must have at least one electron before a single orbital can have two electrons.

Answer 3

hint:
Hund's rule state "the maximum total spin multiplicity" compatibly with the value of energy of an orbital