What will be the correct order for the wavelengths of absorption in the visible region for the following : `[Ni(NO_(2))_(6)]^(4-),[Ni(NH_(3))_(6)]^(2+) lt [Ni(H_(2)O)_(6)]^(2+)`?

Explanation

Positions of ligands in the spectrochemical series as follows : `H_(2)O lt NH_(3) lt NO_(2)^(-)`. So, order of energy of light absorbed by the complexes for `d-d` transition: `[Ni(H_(2)O_(6)]^(2+) lt [Ni(NH_(3))_(6)]^(2+) lt [Ni(NO_(2))_(6)]^(4-)`.
Wavelengths of light absorbed will in the reverse order since `E=hc//lambda`
The correct order of the wavelengths will be :
`[Ni(NO_(2))_(6)]^(4-)lt[Ni(NO_(3))_(6)]^(2+) lt [Ni (H_(2)O)_(6)]^(2+)`