which rule was broken? aufb au principle hunds rule pauli exclusion principle drag

Brief Explanations:

The Aufbau principle states that electrons fill lower - energy orbitals before higher - energy ones. Hund's rule says that in degenerate orbitals, electrons first occupy orbitals singly with parallel spins. The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. In the given electron - filling diagram, the 2p orbitals are not filled according to Hund's rule. Electrons should first singly occupy each 2p orbital with parallel spins before pairing up.

Answer:

Hund's Rule