Number of paramagnetic complexes among the following is ________. [ MnBr ₄]²⁻ , [ NiCl ₄]²⁻ , [ Ni(CN) ₄]²⁻ , [ Ni(CO) ₄] , [ CoF ₆]³⁻ , [ Fe(CN) ₆]⁴⁻ , [ Mn(CN) ₆]³⁻ , [ Ti(CN) ₆]³⁻ , [ Cu(H ₂ O) ₆]²⁺ , [ Co(C ₂ O ₄ ) ₃]³⁻

Step-by-step solution

To determine the magnetic nature of the given complexes, we analyze the oxidation state, electronic configuration, and the nature of the ligands for each central metal atom/ion: 1. [ MnBr ₄]²⁻ : Mn ²⁺ has a 3d^5 configuration. Br ^- is a weak field ligand. The complex is tetrahedral with 5 unpaired electrons. (Paramagnetic) 2. [ NiCl ₄]²⁻ : Ni ²⁺ has a 3d^8 configuration. Cl ^- is a weak field ligand. The complex is tetrahedral with 2 unpaired electrons. (Paramagnetic) 3. [ Ni(CN) ₄]²⁻ : Ni ²⁺ has a 3d^8 configurat