Question

Which one of the transition metal ions is coloured in aqueous solution?

• A. $Cu^{+}$
• B. $Zn^{2+}$
• C. $Sc^{3+}$
• D. $V^{4+}$

Answer 1

Answer: (D)

(a) Valence shell electron configuration of $Cr^{3+}is \left[Ar\right]^{18}3d^{10};so n=0$
(b) Valence shell electron configuration of $Zn^{2+}is \left[Ar\right]^{18}3d^{10};so n=0$ (c) Valence shell electron configuration of $Sc^{3+}is \left[Ar\right]^{18}3d^{0};so n=0$
(d)Valence shell electron configuration of $V^{4+}is \left[Ar\right]^{18}3d^{1};so n=1$
As $V^{4+}$ has one unpaired electron and so in presence of water as ligand it will undergo d-d transition of electron. Hence $V^{4+}$ ions will produce colour in the solution