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JEE Main 20205 SeptemberMorning Shift

Exam: JEE Main
Year: 2020
Date: 5 September
Shift: Morning Shift
Subject: Chemistry
Chapter: d and f Block Elements

JEE Main 2020 · 5 September · Morning Shift · Chemistry · d and f Block Elements

The correct electronic configuration and spin-only magnetic moment...

The correct electronic configuration and spin-only magnetic moment (BM)

of {Gd}^{3 +} ( Z = 64 ) ,

respectively, are :

Options

A $[ Xe ] 4{f}^{7}$ and $8 . 9$
B $[ Xe ] 4{f}^{7}$ and $7 . 9$
C $[ Xe ] 5{f}^{7}$ and $8 . 9$
D $[ Xe ] 5{f}^{7}$ and $7 . 9$

Correct answer

B. $[ Xe ] 4{f}^{7}$ and $7 . 9$

Step-by-step solution

Electronic configuration of

$64Gd = [ Xe ] 4{F}^{7}5{d}^{1}6{s}^{2}$

$Gd 3 + 64 = [ Xe ] 4{F}^{7}$

No. of unpaired electron $= 7$

$\mu = \sqrt{n ( n + 2 )}BM$

$= \sqrt{63}$

$= 7 . 93BM$

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