Q. From the magnetic behaviour of [NiCl₄]²⁻ (paramagnetic) and [Ni(CO)₄] (diamagnetic), choose the correct geometry and oxidation state.
A) [NiCl₄]²⁻ : Ni(II), tetrahedral; [Ni(CO)₄] : Ni(II), square planar
B) [NiCl₄]²⁻ : Ni(II), square planar; [Ni(CO)₄] : Ni(0), square planar
C) [NiCl₄]²⁻ : Ni(II), tetrahedral; [Ni(CO)₄] : Ni(0), tetrahedral
D) [NiCl₄]²⁻ : Ni(0), tetrahedral; [Ni(CO)₄] : Ni(0), square planar
Explanation
[Solution by Dr. Abubacker] Cl⁻ is a weak-field ligand, so Ni²⁺ (d⁸) forms the paramagnetic tetrahedral [NiCl₄]²⁻. CO is a strong-field ligand: Ni(0) (3d¹⁰, sp³) gives the diamagnetic tetrahedral [Ni(CO)₄]. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.