Which of the following complex compound exhibits cis-trans isomerism? — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: A complex is attracted by a magnetic field if it is paramagnetic (has one or more unpaired electrons). Step 2: Determine the electronic states of each complex: (I) [Ni(CN)4]^2- is square planar d^8 low-spin (0 unpaired electrons); (II) [NiCl4]^2- is tetrahedral d^8 high-spin (2 unpaired electrons); (III) Ni(CO)4 is tetrahedral d^10 (0 unpaired electrons); (IV) [Ni(H2O)6]^2+ is octahedral d^8 high-spin (2 unpaired electrons). Step 3: Since only (II) and (IV) contain unpaired electrons, they are attracted by a magnetic field, which corresponds to option (d).