Final answer:
Hund's rule violation can occur in the subshells: p only, d only, and p and d.
Step-by-step explanation:
Hund's rule states that electrons will arrange in the degenerate set of orbitals with one electron in each orbital with like spins before any pairing occurs. This means that Hund's rule violation can only occur in subshells that have a degenerate set of orbitals, where there are two or more orbitals of the same energy. The subshells where Hund's rule violation can occur are p only, d only, and p and d.