Phosphorus trichloride (PCl3) is a polar covalent molecule with a trigonal pyramidal geometry. The intermolecular force present in PCl3 is dipole-dipole interaction.

Dipole-dipole interaction is an attractive force that arises between polar molecules. It occurs when the positive end of one molecule is attracted to the negative end of another molecule. In the case of PCl3, the P-Cl bonds are polar due to the difference in electronegativity between phosphorus and chlorine. This results in a net positive charge on the phosphorus atom and a net negative charge on the chlorine atoms. The interaction between these polar bonds gives rise to dipole-dipole forces between PCl3 molecules.