Question

The correct order of the wavelength maxima of the absorption band in the ultraviolet-visible region for the given complexes is

Accepted Answer

(A) $\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}(\mathrm{Cl})\right]^{2+}$

Answer

(B) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}(\mathrm{Cl})\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}<\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}$

Answer

(C) $\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}(\mathrm{Cl})\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$

Answer

(D) $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}<\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}(\mathrm{Cl})\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}$

JEE Advanced · 2025 · 18 May 2025 · Paper 1 · Coordination Compounds

Solution

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