JEE Main 2018 — Coordination Compounds Question with Solution
From: JEE Main 2018 (Online) 15th April Evening Slot
Question
The correct order of spin-only magnetic moments among the following is :
(Atomic number : Mn = 25, Co = 27, Ni = 28, Zn = 30)
(Atomic number : Mn = 25, Co = 27, Ni = 28, Zn = 30)
Choose an option
Show full solutionCorrect option: D
Correct answer
D[MnCl4]2- > [CoCl4]2- > [NiCl4]2- > [ZnCl4]2-
Step-by-step explanation
We know,
Spin only magnetic moment () = B.M
Where, n is the number of unpaired electrons.
So, the complex having higher number of unpaired electrons will have higher value of spin only magnetic moment.
(1) Zn+2 : [Ar] 3d10
Here 0 unpaired electrons present
(2) Ni+2 : [Ar] 3d8
Here 2 unpaired electrons present.
(3) Co+2 : [Ar] 3d7
Here 3 unpaired electrons present.
(4) Mn+2 : [Ar] 3d5
Here 5 unpaired electrons present.
So, correct order is
[MnCl4]2 > [CoCl4]2 > [NiCl4]2 > [ZnCl4]2
Spin only magnetic moment () = B.M
Where, n is the number of unpaired electrons.
So, the complex having higher number of unpaired electrons will have higher value of spin only magnetic moment.
(1) Zn+2 : [Ar] 3d10
Here 0 unpaired electrons present
(2) Ni+2 : [Ar] 3d8
Here 2 unpaired electrons present.
(3) Co+2 : [Ar] 3d7
Here 3 unpaired electrons present.
(4) Mn+2 : [Ar] 3d5
Here 5 unpaired electrons present.
So, correct order is
[MnCl4]2 > [CoCl4]2 > [NiCl4]2 > [ZnCl4]2
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This is a previous-year question from JEE Main 2018, covering the Coordination Compounds chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.