(a) [Ni(CN)4]2− Ni+2=3d8 2 unpaired electrons are presence. ∴ Nature = paramagnetic Shape = square planar (b) [Ni(CO)4] Ni=3d84s2 Shape = tetrahedral As CO is strong ligand, it causes pairing of electrons, therefore nature is diamagnetic. (c) [Ni(Cl)4]2− Ni2+=3d8 Shape = tetrahedral As Cl− is weak ligand, no pairing occurs therefore, nature is paramagnetic. (d) [Ni(NH3)6]2+ Ni2+=3d84s0 Shape = octahedral and nature is paramagnetic.