QJEEM18Cha5c1: JEE Main 2018 Chemistry - Class 12 JEEM18Cha5c1 Solution: The correct order of spin-only magnetic moments among the…

We know,

Spin only magnetic moment ( $\mu$ ) = $\sqrt {n\left( {n + 2} \right)}$   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 $\to$
    [MnCl₄]^{2 $-$} > [CoCl₄]^{2 $-$} > [NiCl₄]^{2 $-$} > [ZnCl₄]^{2 $-$}