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Chemistry · PYQ NEET UG 2017
हिन्दीCORRECT increasing order for the wavelengths of absorption in the visible region of the complexes of \( \text{Co}^{3+} \) is
Correct answer · Option 4
\( [\text{Co}(\text{en})_3]^{3+} < [\text{Co}(\text{NH}_3)_6]^{3+} < [\text{Co}(\text{H}_2\text{O})_6]^{3+} \)
Explanation
Crystal field splitting (\( \Delta_0 \)) increases in the order: \( \text{H}_2\text{O} < \text{NH}_3 < \text{en} \). Since wavelength \( \lambda \propto \frac{1}{\Delta_0} \), the wavelength order is reverse: \( [\text{Co}(\text{en})_3]^{3+} < [\text{Co}(\text{NH}_3)_6]^{3+} < [\text{Co}(\text{H}_2\text{O})_6]^{3+} \).
