On reaction with acid, 4-pyrone is protonated on the carbonyl-group oxygen to give a stable cationic product. Draw a resonance structure that illustrates why the protonated product is so stable.

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.