Which among the following cations produces colourless aqueous solution in their respective oxidation state?
Which among the following cations produces colourless aqueous solution in their respective oxidation state?
$\mathrm{Ti}^{3+}$
$\mathrm{V}^{3+}$
$\mathrm{Sc}^{3+}$
$\mathrm{Cu}^{2+}$
Solution
Condensed electronic configuration of: $\mathrm{Sc}^{3+}$ : [Ar] $3 \mathrm{~d}^0 . \mathrm{Sc}^{3+}$ ion has completely empty $3 \mathrm{~d}-$ orbital, i.e., no unpaired electrons are present. As d-d transitions are not possible, $\mathrm{Sc}^{3+}$ ion is colourless.