Which of the following statements are correct? i. [ Mn ( CN )₆ ]³⁻, [ MnCl ₆ ]³⁻ both are paramagnetic ii. Both [ NiCl ₄ ]²⁻, [ Ni ( CO )₄ ] are tetrahedral and diamagnetic iii. [ Co ( NH ₃ )₆ ]³⁺ is inner orbital complex, but [ Ni ( NH ₃ )₆ ]²⁺ is outer orbital complex

Step-by-step solution

[ NiCl ₄ ]²⁻ has Ni ²⁺ that has the configuration [ Ar ] 3 ~d ^8 . Since Cl ⁻ is a weak-field ligand, the configuration of the complex will be:- [ NiCl ₄ ]²⁻= Thus, it is a tetrahedral complex. It is paramagnetic due to unpaired electrons. [ Ni ( CO )₄ ] has neutral and strong-field ligand CO . Thus, [ Ni ( CO )₄ ]= Thus, [ Ni ( CO )₄ ] is a square-planar and diamagnetic complex. Therefore, (ii) is incorrect and only (i) and (iii) are correct.