Nickel (Z = 28) combines with a uninegative monodentate ligand to form a diamagnetic complex NiL 4 2 − . The hybridisation involved and the number of unpaired electrons present in the complex are respectively:

Step-by-step solution

​ 28 Ni has +2 oxidation state and since the complex is Diamagnetic, all electrons are paired in inner 3d, orbital to provide the electronic configuration as under: L − might have been a strong field like CN − . Hybridisation is dsp 2 . Number of unpaired electrons = 0