The PCl5 molecule has trigonal bipyramidal structure. Therefore,the hybridization of p orbitals should be

The P atom needs five orbitals to form the five P-Cl bonds. It has a 3s and three 3p orbitals, so it must use one of its 3d orbitals to form the fifth bond. These orbitals are hybridized to form five sp3d orbitals that just happen to point in the right directions to form a trigonal bipyramid.