Assertion : Bond lengths of P - Cl bonds in gaseous PCl ₅ and solid PCl ₅ are not equal. Reason : Because in solid state two PCl ₅ molecules are associated.

Step-by-step solution

As in solid state, PCl ₅ exists as an ionic solid [ PCl ₄ ]⁺ [ PCl ₆ ]⁻ in which the cation, [ PCl ₄ ]⁺ is tetrahedral and the anion, [ PCl ₆ ]⁻ is octahedral. PCl ₅ in gaseous state has trigonal bipyramidal structure in which three equatorial bonds are equivalent, while the two axial bonds are longer than equatorial bonds due to more bond pair repulsion.