Question

Which one of the following metal ions is coloured ?

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

Answer 1

Answer: (D)

$V^{4+}$

Answer 2

$Cu^+ : [Ar]^{18} \, 3d^{10} ; Zn^{2+} : [Ar]^{18} \, 3d^{10}$ $Sc^{3+} : [Ar]^{18} 3d^0 ; V^{4+} : [Ar]^{18} \, 3d^1$ Out of these four ions only $V^{4+}$ is coloufed as all other ions have either $d^{10}$ configuration or $d^{0}$ configurationi.e., without any unpaired electron, since ions with one or more unpaired electrons are coloured.