The absorption of  ${\left[Co{\left(N{H}_3\right)}_6\right]}^{2+}$ is

Since ammonia is stronger ligand  ${\Delta }_0$ is more than  ${\Delta }_t$. Further with increase in the number of charges on $C{o}^{3+}$  in  ${\left[Co{\left(N{H}_3\right)}_{5}Cl\right]}^{2+}.{\Delta }_0$ is more in ${\left[Co{\left(N{H}_3\right)}_6\right]}^{2+}$  than in  ${\left[Co{\left(N{H}_3\right)}_{5}Cl\right]}^{2+}$. So absorption of energy is more in   than   ${\left[Co{\left(N{H}_3\right)}_6\right]}^{2+}$and  ${\left[MnC{l}_4\right]}^{2-}$