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

Explanation

In all the given complexes, the metal ion is `Ni^(2+)`. The increasing field strengths of the ligands present as per spectrochemical series are in the order:
`[Ni(H_(2)O)_(6)]^(2+)lt[Ni(NH_(3))_(6)]^(2+)lt[Ni(NO_(2))_(6)]^(4-)`
As `E=hc//lamda`
It implies that wavelength is inversely proportional to energies. So, order for the wavelength of absorption is
`[Ni(H_(2)O)_(6)]^(2+)gt[Ni(NH_(3))_(6)]^(2+)gt[Ni(NO_(2))_(6)]^(4-)`