The correct order of the wavelength maxima of the absorption band in the ultraviolet-visible region for the given complexes is:
\( [\mathrm{Co(CN)}_{6}]^{3-} \lt [\mathrm{Co(NH_3)}_{6}]^{3+} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{H_2O})]^{3+} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{Cl})]^{2+} \)
\( [\mathrm{Co(NH_3)}_{5}(\mathrm{Cl})]^{2+} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{H_2O})]^{3+} \lt [\mathrm{Co(NH_3)}_{6}]^{3+} \lt [\mathrm{Co(CN)}_{6}]^{3-} \)
\( [\mathrm{Co(CN)}_{6}]^{3-} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{Cl})]^{2+} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{H_2O})]^{3+} \lt [\mathrm{Co(NH_3)}_{6}]^{3+} \)
\( [\mathrm{Co(NH_3)}_{6}]^{3+} \lt [\mathrm{Co(CN)}_{6}]^{3-} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{Cl})]^{2+} \lt [\mathrm{Co(NH_3)}_{5}(\mathrm{H_2O})]^{3+} \)