The number of p atomic orbitals involved in the formation of a benzene molecule.

The six pi molecular orbitals in benzene, which are created from six atomic p orbitals, are calculated to occupy four different energy levels. The bonding orbitals are fully filled and the antibonding orbitals are left empty when we apply the Aufbau principle to fill these orbitals with the six pi electrons in benzene. 

Therefore, the number of p atomic orbitals involved in the formation of a benzene molecule is 6.