I think the answer is D, PCl5. Ionic compounds are compounds made up of ions. These ions are atoms that gain or lose electrons to form a stable configuration, thus attaining a net positive charge or negative charge. Metals tend to lose electrons thus they become cations and have a net positive charge. On the other hand non-metals tend to gain electrons, forming anions that have a net negative charge. Phosphorus chloride is not an ionic compound since it is made up of phosphorus and chlorine which are both non metals.
