Question

Which of the following ions will exhibit colour in aqueous solutions?

• A. La${}^{3+}$ (z = 57)
• B. Ti${}^{3+}$ (z = 22)
• C. Lu ${}^{3+}$ (z = 71)
• D. Sc${}^{3+}$ (z = 21)

Answer 1

The correct option is B Ti${}^{3+}$ (z = 22)

The ion which have unpaired electron shows colour

$\left(A\right)$ $La=\left[Xe\right]5d^{1}6s^2$

$L{a}^{+3}=\left[Xe\right]0$ unpaired electron.

$\left(B\right)$ $Ti=\left[Ar\right]3d^{2}4s^2$

$T{i}^{+3}=\left[Ar\right]3d^{1}1$ unpaired electron.

$\left(C\right)$ $Lu=\left[Xe\right]4f^{14}5d^{1}6s^2$

$L{u}^{+3}=\left[Xe\right]4f^{14}0$ unpaired electron.

$\left(D\right)$ $Sc=\left[Ar\right]3d^{1}4s^2$

$S{c}^{+3}=\left[Ar\right]0$ unpaired electron.