NiCl ₂ P ( C ₂ H ₅ )₂ ( C ₆ H ₅ ) ₂ exhibits temperature depend-ent magnetic behaviour (paramagnetic/diamagnetic). The coordination geometries of Ni ²⁺ in the paramagnetic and diamagnetic states are respectively

Step-by-step solution

In both states (paramagnetic and diamagnetic) of the given complex, Ni exists as Ni ²⁺ whose electronic configuration is [ Ar ] 3 d⁸ 4 s⁰ . In the above paramagnetic state the geometry of the complex is s p³ giving tetrahedral geometry. The diamagnetic state is achieved by pairing of electrons in 3 d orbital. Thus, the geometry of the complex will be d s p² giving square planar geometry.