Question

Phosphorus pentachloride

• A. On hydrolysis gives an oxo acid of phosphorus which is tribasic
• B. On hydrolysis gives an oxo acid of phosphorus which is a good reducing agent
• C. Has all the five equivalent bonds
• D. Exists as an ionic solid in which cation has octahedral structure and anion has tetrahedral structure

Answer 1

The Correct Option is A

Phosphorus pentachloride (\( \text{PCl}_5 \)) exists as an ionic solid in its solid state. It dissociates into \( \text{P}^{5+} \) cations and \( \text{Cl}^- \) anions. The cation \( \text{P}^{5+} \) adopts an octahedral geometry, while the chloride anions (\( \text{Cl}^- \)) adopt a tetrahedral geometry. This is characteristic of the ionic form of \( \text{PCl}_5 \).
1. Option (B): On hydrolysis, \( \text{PCl}_5 \) gives phosphoric acid (\( \text{H}_3\text{PO}_4 \)), which is tribasic (not the oxo acid mentioned).
2. Option (C): The oxo acid formed from \( \text{PCl}_5 \) hydrolysis is phosphoric acid, which is not a good reducing agent.
3. Option (D): In phosphorus pentachloride, phosphorus forms five bonds, but they are not all equivalent due to different electronegativities of the chlorine atoms.

Thus, the correct answer is (A), where \( \text{PCl}_5 \) exists as an ionic solid with an octahedral cation and a tetrahedral anion.