The correct order about the number of unpaired electrons present in the following complexes is . [ Fe ( CN )₆ ]⁴⁻ II [ Fe ( H ₂ O )₆ ]²⁺ III Co ( H ₂ O )₆ ]²⁺

Step-by-step solution

I. [ Fe ( CN )₆ I ⁴⁻ . Atomic number of Fe =26 Ground state configuration of Fe =[ Ar ] 3 d^6 4 s^2 Fe ²⁺=[ Ar ] 3 d^6 Since, cyanide is a powerful ligand, therefore, all the electrons will be paired. Number of unpaired electrons in [ Fe ( CN )₆ ]⁴⁻=0 II. [ Fe ( H ₂ O )₆ ]²⁺ Atomic number of Fe =26 Ground state configuration of Fe =[ Ar ] 3 d^6 4 s^2 Fe ²⁺=[ Ar ] 3 d^6 Number of unpaired electrons in [ Fe ( H ₂ O )₆ ]²⁺=4 III. [ Co ( H ₂ O )₆ ]²⁺ Atomic number of Co =27 Ground state configuration of Fe =[ Ar ] 3 d^