What are the geometries of PCl5, PCl4, and PCl6 in their respective phases?

The correct choice identifies the geometries of the phosphorus chlorides based on their molecular shapes arising from the spatial arrangement of their bonding and non-bonding electron pairs.

PCl5 exhibits a trigonal bipyramidal geometry. This is due to the presence of five chlorine atoms bonded to the central phosphorus atom, with no lone pairs on the phosphorus. The arrangement allows for three chlorine atoms to occupy equatorial positions in a plane and two to occupy axial positions, minimizing repulsion between the bonds.

PCl4 possesses a see-saw geometry. This shape results when one of the equatorial positions in the trigonal bipyramidal arrangement is occupied by a lone pair of electrons, leading to a distortion of the geometry. The remaining four bonded atoms (three chlorines in equatorial positions and one axial) create a see-saw shape, as the lone pair exerts stronger repulsion than the bonded pairs.

PCl6 has an octahedral geometry, which is characteristic of six bonded pairs of electrons arranged around a central atom. When phosphorus bonds with six chlorine atoms, the model reflects a symmetrical octahedral shape, where the chlorines are positioned 90 degrees apart, leading to an optimal distribution of electron pairs and minimizing electron pair repuls