Correct increasing order for the wavelengths of absorption in the visible region by the complexes of `Co^(3+)` is:

Options

A. `[Co(H_(2)O)_(6)]^(3+), [Co(en)_(3)]^(3+), [Co(NH_(3))_(6)]^(3+)`
B. `[Co(H_(2)O)_(6)]^(3+), [Co(NH_(3))_(6)]^(3+), [Co(en)_(3)]^(3+)`
C. `[Co(H_(2)O)_(6)]^(3+), [Co(en)_(3)]^(3+), [Co(H_(2)O)_(6)]^(3+)`
D. `[Co(en)_(3)]^(3+), [Co(NH)_(3))_(6)]^(3+), [Co(H_(2)O)_(6)]^(3+)`

Answer

D

Explanation

`Delta E prop` field of ligand strength `prop (1)/(lambda)`
correct order of field strength of ligand:
`H_(2) O lt NH_(3) lt en`