Question

Which of the following metal ions is expected to be coloured?

• A. $Zn^{2+}$
• B. $Ti^{3+}$
• C. $sc^{3+}$
• D. $Ti^{4+}$

Answer 1

Answer: (B)

$Ti^{3+}$

Answer 2

$Ti^{3+}$ has one unpaired electron in $d$-orbital In aqueous solution this electron undergoes $d-d$ transition and impart colour. In $Zn^{2+}$, $Sc^{3+}$ and $Ti^{4+}$, no unpaired electron is present in $d$-orbital hence, they won't impart colour