Question

Match the metal ions given in Column I with the spin magnetic moments of the ions given in Column II and assign the correct code :

Column I		Column II
a.	$Co^{3+}$	i.	$\sqrt{8} B.M$
b.	$Cr^{3+}$	11.	$\sqrt{35} B.M$
c.	$Fe^{3+}$	iii.	$\sqrt{3} B.M$
d	$Ni^{2+}$	iv	$\sqrt{24} B.M$
		v	$\sqrt{15} B.M$

• A. a - iii , b - v , c - i , d - ii
• B. a - iv , b - v , c - ii , d - i
• C. a - iv , b - i, c - ii , d - iii
• D. a - i , b - ii , c - iii , d - iv

Answer 1

Answer: (B)

$Co ^{3+}=[ Ar ] \,3 d ^{6}$, Unpaired $e ^{-}( n )=4$

Spin magnetic moment $=\sqrt{4(4+2)}=\sqrt{24}\, BM$

$Cr ^{3+}=[ Ar ] \,3 d ^{3}$, Unpaired $e ^{-}( n )=3$

Spin magnetic moment $=\sqrt{3(3+2)}=\sqrt{15} \,BM$

$Fe ^{3+}=[ Ar ] \,3 d ^{5}$, Unpaired $e ^{-}( n )=5$

Spin magnetic moment $=\sqrt{5(5+2)}=\sqrt{35} \,BM$

$Ni ^{2+}=[ Ar ] \,3 d ^{8}$, Unpaired $e ^{-}( n )=2$

Spin magnetic moment $=\sqrt{2(2+2)}=\sqrt{8}\, BM$