The d electron configuration of Cr ²⁺ , Mn ²⁺, Fe ²⁺ and Ni ²⁺ are 3 ~d ^4, 3 ~d ^5, 3 ~d ^6 and 3 ~d ^8 respectively. Which one of the following aqua complexes will exhibit the minimum paramagnetic behaviour? (At. No. Cr =24, Mn =25, Fe =26, Ni = 28)

Step-by-step solution

aligned & Cr ⁺⁺ (3 ~d ^4 )= array |l|l|l|l|l| 1 & 1 & 1 & 1 & array & =4 unpaired e⁻ & Mn ⁺⁺ (3 ~d ^4 )= array |l|l|l|l|l| 1 & 1 & 1 & 1 & 1 array & =5 unpaired e⁻ & Fe ⁺⁺ (3 ~d ^6 )= array |l|l|l|l|l| 1L & 1 & 1 & 1 & 1 array & =4 unpaired e⁻ & Ni ⁺⁺ (3 ~d ^8 )= array |l|l|l|l|l| 1h & 1L & IL & 1 & 1 array & =2 unpaired e⁻ & aligned As Ni ⁺⁺ has minimum no. of unpaired e⁻ thus this is least paramagnetic.