Chemistry - Complete d-block Question with Solution | TestHub

Atomic number of Ag, Hg, Zn and Co is 47, 80, 30 and 27 respectively.

Write the electronic configuration of each and see if there are any unpaired electrons.

$\mathrm{In\; C}\mathrm{o}\mathrm{C}{\mathrm{l}}_3-\mathrm{C}{\mathrm{o}}^{+3}-\mathrm{[Ar]3}{\mathrm{d}}^{6}4{\mathrm{s}}^0$

4 unpaired electrons. So, it will be coloured.