Means all ligands behaves as weak field ligands
\(=[-0.4 \times 4+0.6 \times 2] \Delta_{0}\)
\(=[-1.6+1.2] \Delta_{0}\)
\(=\left[-0.4 \Delta_{0}\right]\)
$(I)\, [CrCl_2(NO_2)_2(NH_3)_2]^-$ $(II)\, [Co(NO_2)_3(NH_3)_3]$
$(III)\, [PtCl(NO_2)(NH_3 )(py)]$ $(IV)\, [PtBrCl(en)]$
$(I)\,\,\,-\,\,\,(II)\,\,\,-\,\,\,(III)\,\,\,-\,\,\,(IV)$