Q. Of the following complex ions, which is diamagnetic in nature?
A) [CoF₆]³⁻
B) [NiCl₄]²⁻
C) [Ni(CN)₄]²⁻
D) [CuCl₄]²⁻
Explanation
[Solution from source] Ni²⁺ is d⁸; strong-field CN⁻ pairs all electrons and gives a dsp² square planar complex with no unpaired electrons, so [Ni(CN)₄]²⁻ is diamagnetic. [NiCl₄]²⁻ is tetrahedral sp³ with 2 unpaired electrons, [CoF₆]³⁻ has 4 and [CuCl₄]²⁻ (d⁹) has 1. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.