Chemistry - Complete d-block Question with Solution | TestHub

$\mathrm{d}$-block elements form coloured ions due to presence of unpaired electrons in them. since there are no unpaired electrons in ${\mathrm{Sc}}^{3+}$ and ${\mathrm{Zn}}^{2+}$ ions, they are colourless.

No of unpaired ${\mathrm{e}}^{-}$

 ${\mathrm{Ti}}^{3+}-\left[\mathrm{Ar}\right]3 {\mathrm{d}}^1,{\mathrm{Cu}}^{2+}-\left[\mathrm{Ar}\right]3 {\mathrm{d}}^9$

${\mathrm{Sc}}^{3+}-\left[\mathrm{Ar}\right]3 {\mathrm{d}}^0,{\mathrm{Zn}}^{2+}-\left[\mathrm{Ar}\right]3 {\mathrm{d}}^{10}$

$T{i}^{4+}-\left[\mathrm{Ar}\right]3 {\mathrm{d}}^0 {\mathrm{V}}^{2+}-\left[\mathrm{Ar}\right]3 {\mathrm{d}}^3 ,$

No d-d transitions in ions with ${\mathrm{d}}^0$ & ${\mathrm{d}}^{10}$ configuration. Therefore they are colourless.