Chemistry - Complete d-block Question with Solution | TestHub

The electronic configurations of cations in the given salts are as follows
$\mathrm{C}{\mathrm{u}}^{+}\left(3{\mathrm{d}}^{10}\right),\mathrm{C}{\mathrm{u}}^{2+}\left(3{\mathrm{d}}^9\right),\mathrm{A}{\mathrm{g}}^{+}\left(4{\mathrm{d}}^{10}\right),\mathrm{}\mathrm{M}{\mathrm{g}}^{2+}\left(2{\mathrm{s}}^{2}2{\mathrm{p}}^6\right)$
Hence only$\mathrm{C}{\mathrm{u}}^{2+}$ion has one unpaired electron in 3d orbital it means d-d electronic transition is possible, so its salt is coloured.