CGPET 2019 Solved Paper

(a) In [Cu(NH3)4]2+, in the presence of ligand NH3,Cu2+ ions show the following electronic configuration. Note In which one electron of 3d is transfered to 4p.
The above complex show colour due to d−d transition.
(b) In CrO42−, Cr in compound CrO42− offer colour due to charge transfer from metal to π* orbitals of ligand and not due to d−d transition.
(c) In [CoF6]3−, in the presence of weak ligand (i.e. fluorine), Co3+ ions show the following electronic configuration,
The above complex has unpaired electrons and can show colour due to d−d transition.
(d) In [Ti(H2O)6]3+The presence of weak ligand i.e., (H2O),Ti3+ ion show one unpaired electron and offer colour due to d−d transition.
Hence, option (b) is the correct answer.