Question

In solid state, PCl₅ is a/an

• A. Octahedral structure
• B. Ionic solid with [PCl₆]⁺ and [PCl₄]^-
• C. Ionic solid with [PCl₄]⁺ and [PCl₆]^-
• D. Covalent solid present in the form of P₂Cl₁₀

Answer 1

The Correct Option is C

In solid state, PCl₅ forms an ionic compound. The phosphorus atom (P) has an empty 3d orbital and can expand its octet to form a compound with more than four bonds. In PCl₅, it forms five bonds with chlorine atoms, but in the solid state, it forms an ionic compound by losing one electron to form a cation [PCl₄]⁺ and gaining an electron to form an anion [PCl₆]^-.

Why is option (C) correct?

• PCl₅ forms an ionic compound in the solid state.
• The cation formed is [PCl₄]⁺ and the anion formed is [PCl₆]^-.

Why are the other options incorrect?

• Option (A): PCl₅ does not have an octahedral structure in the solid state.
• Option (B): The ions are reversed. The correct ions are [PCl₄]⁺ and [PCl₆]^-.
• Option (D): PCl₅ does not form a covalent solid in the form of P₂Cl₁₀.

Conclusion: The correct answer is (C) Ionic solid with [PCl₄]⁺ and [PCl₆]^- because PCl₅ forms an ionic compound in the solid state with these specific ions.

Answer 2

In the solid state, PCl₅ exhibits ionic character and forms a crystal structure in which it dissociates into ions. The structure of PCl₅ in the solid state consists of both \( [PCl_4]^+ \) and \( [PCl_6]^- \) ions.

Option A (Octahedral structure)**: This is incorrect because PCl₅ in its solid state does not adopt an octahedral structure.
Option B (Ionic solid with \( [PCl_6]^+ \) and \( [PCl_4]^- \))**: This is incorrect because the charges on the ions are reversed.
Option C (Ionic solid with \( [PCl_4]^+ \) and \( [PCl_6]^- \))**: This is correct. In the solid-state structure of PCl₅, it exists as an ionic solid with these ions.
Option D (Covalent solid present in the form of \( P_2Cl_{10} \))**: This is incorrect because PCl₅ in the solid state exists as ionic solids, not covalent molecules like \( P_2Cl_{10} \).

Thus, the correct answer is: \({\text{(C) Ionic solid with } [PCl_4]^+ \text{ and } [PCl_6]^-}\)