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Question:

Correct increasing order for the wavelength of absorption in the visible region for the complexes of Co3+ is?

[Co(CN)6]3−,[Co(NH3)6]3+,[Co(NH3)5(H2O)]3+[Co(NH3)

[Co(NH3)6]3+,[Co(CN)6]3−,[Co(NH3)5(H2O)]3+[Co(NH3)

[Co(CN)6]3−,[Co(NH3)5(H2O)]3+[Co(NH3)5Cl]+2[Co(NH

[Co(NH3)5Cl]+2,[Co(NH3)5(H2O)]3+,[Co(NH3)6]3+,[Co(CN

Solution:

Correct option is A. [Co(CN)6]3−,[Co(NH3)6]3+,[Co(NH3)5(H2O)]3+[Co(NH3)Strength of ligands attached with Co3+ ion is in the order of CN−>NH3>H2O>Cl−. So order of splitting (value of Δ0) will be in the same order. Therefore, Wavelength ∝ 1/Δ0. Thus the correct increasing order of wavelength is- [Co(CN)6]3−<[Co(NH3)6]3+<[Co(NH3)5(H2O)]3+<[Co(NH3)Hence, the correct option is A