Question

Which one of the following ionic species will impart colour to an aqueous solution?

• A. $T{i}^{4+}$
• B. $C{u}^{+}$
• C. $Z{n}^{2+}$
• D. $C{r}^{3+}$

Answer 1

Answer: (D)

Here $C{r}^{3+}$ is coloured while rest other ions are coloureless.

$T{i}^{4+}=[Ar]4s^{0}3d^0$ (0 unpaired $e^{-}$ )

$C{u}^{+}=[Ar]4s^{0}3d^{10}$ (0 unpaired $e^{-}$ )

$Z{n}^{2+}=[Ar]4s^{0}3d^{10}$ (0 unpaired $e^{-}$ )

$C{r}^{3+}=[Ar]4s^{0}3d^3$ (3 unpaired $e^{-}$ )