Chemistry - Coordination Chemistry Question with Solution | TestHub

In ${\left[\mathrm{Co}(\mathrm{en}{)}_3\right]}^{+3}$ S.F.L. is present and hence highest value of CFSE
In rest all complexes WFL is present hence CFSE will be low.
${\left[\mathrm{Co}(\mathrm{en}{)}_3\right]}^{+3}\Rightarrow {\mathrm{Co}}^{+3}$ and en (SFL)
${\mathrm{Co}}^{+3}\Rightarrow [\mathrm{Ar}]3{\mathrm{d}}^6$