Which of the following is the IUPAC name for PCl5?

The correct IUPAC name for PCl5 is phosphorous pentachloride. This name accurately reflects the chemical structure of the compound, where "phosphorous" indicates the oxidation state of phosphorus, which is +5 in this case. The prefix "penta-" denotes the presence of five chlorine atoms bonded to the phosphorus atom.

Using the correct naming conventions, the prefix indicates the number of atoms of chlorine in the molecule, and the term "chloride" indicates that chlorine is acting as a non-metal ion in this compound. Naming the compound as "phosphorous" rather than "phosphoric" is important because it corresponds to the specific valence state of phosphorus in this particular compound.

The other options do not accurately describe PCl5:

• "Phosphorus dichloride" suggests the presence of only two chlorine atoms.

• "Phosphorus trichloride" indicates three chlorine atoms, which does not represent PCl5.

• "Phosphorus chlorate" implies a different structure involving a polyatomic ion, which does not apply to PCl5.

Thus, phosphorous pentachloride correctly conveys the composition and oxidation state of the compound.