Strong ligand $\alpha $  $CFSE$   $\alpha $ ${E_{absorbed}}\,\propto \,\frac{1}{{{\lambda _{absorbed}}}}$

We have

$\mathop {{{[CoCl{{(N{H_3})}_5}]}^{2 + }}}\limits_{(I)} ,$  $\mathop {{{[Co{{(N{H_3})}_5}{H_2}O]}^{3 + }}}\limits_{(II)} $  and $\mathop {{{[Co{{(N{H_3})}_6}]}^{3 + }}}\limits_{(III)} $

$\therefore \,III\, > \,II\, > \,I$  (as per ${E_{absorbed}}$ )

$\therefore \,\,\frac{1}{{{\lambda _{absorbed}}}}$

$I\, > \,II\, > \,III$