નીચેના પૈકી ફકત સ્પીન આધારિત ચુંબકીય ચાકમાત્રાનો સાચો ક્રમ જણાવો.

(પ.ક્ર.: $Mn\, = 25, Co\, = 27, Ni\, = 28, Zn\, = 30$)

Question

નીચેના પૈકી ફકત સ્પીન આધારિત ચુંબકીય ચાકમાત્રાનો સાચો ક્રમ જણાવો.

(પ.ક્ર.: $Mn\, = 25, Co\, = 27, Ni\, = 28, Zn\, = 30$)

A${\left[ {ZnC{l_4}} \right]^{2 - }} > {\left[ {NiC{l_4}} \right]^{2 - }} > {\left[ {CoC{l_4}} \right]^{2 - }} > {\left[ {MnC{l_4}} \right]^{2 - }}$
B${\left[ {CoC{l_4}} \right]^{2 - }} > {\left[ {MnC{l_4}} \right]^{2 - }} > {\left[ {NiC{l_4}} \right]^{2 - }} > {\left[ {ZnC{l_4}} \right]^{2 - }}$
C${\left[ {NiC{l_4}} \right]^{2 - }} > {\left[ {CoC{l_4}} \right]^{2 - }} > {\left[ {MnC{l_4}} \right]^{2 - }} > {\left[ {ZnC{l_4}} \right]^{2 - }}$
D${\left[ {MnC{l_4}} \right]^{2 - }} > {\left[ {CoC{l_4}} \right]^{2 - }} > {\left[ {NiC{l_4}} \right]^{2 - }} > {\left[ {ZnC{l_4}} \right]^{2 - }}$

JEE MAIN 2018, Diffcult

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Solution

d
The complex having higher number of unpaired electrons will have higher value of spin only magnetic moment.

In all these complexes, the central metal ion is in $+2$ oxidation state.

$Zn^{2+}$ has $3d^{10}$ outer electronic configuration with $0$ unpaired electron.

$Ni^{2+}$ has $3d^8$ outer electronic configuration with $2$ unpaired electrons.

$Co^{2+}$ has $3d^7$ outer electronic configuration with $3$ unpaired electrons.

$Mn^{2+}$ has $3d^5$ outer electronic configuration with $5$ unpaired electrons.

Hence the correct order of spin - only magnetic moments is

${[MnC{l_4}]^{2 - }}\, > \,{[CoC{l_4}]^{2 - }}\, > \,{[NiC{l_4}]^{2 - }}\, > \,{[ZnC{l_4}]^{2 - }}$

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