Coordination Compounds - Result Question 55
####62. Which of the following complex ions is expected to absorb visible light?
[2009]
(a) $[Ti(en)_2(NH_3)_2]^{4+}$
(b) $[Cr(NH_3)_6]^{3+}$
(c) $[Zn(NH_3)_6]^{2+}$
(d) $[Sc(H_2 O)_3(NH_3)_3]^{3+}$
(At. no. $Zn=30, Sc=21, Ti=22, Cr=24$ )
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Solution:
- (b) Since $Cr^{3+}$ in the complex has unpaired electrons in the d orbital, hence will be coloured $Ti=[Ar] 3 d^{2} 4 s^{2}$ $Ti^{4+}=3 d^{0}$
$Cr=[Ar] 3 d^{5} 4 s^{1}$
$Cr^{3+}=3 d^{3}$
$ \begin{matrix} Zn=[Ar] 3 d^{10} 4 s^{2} ; & Zn^{2+}=3 d^{10} \\ Sc=[Ar] 3 d^{1} 4 s^{2} ; & Sc^{3+}=3 d^{0} \end{matrix} $
