Which among the following is a correct decreasing order of thermodynamic stability of the complexes?

Which among the following is a correct decreasing order of thermodynamic stability of the complexes?
  1. $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}\gt\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{-}\gt\left[\mathrm{Cu}(\mathrm{CN})_4\right]^{2-}$
  2. $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}\gt\left[\mathrm{Cu}(\mathrm{CN})_4\right]^{2-}\gt\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{-}$
  3. $\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{-}\gt\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}\gt\left[\mathrm{Cu}(\mathrm{CN})_4\right]^{2-}$
  4. $\left[\mathrm{Cu}(\mathrm{CN})_4\right]^{2-}\gt\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{--}\gt\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$.

Solution

Higher the charge on the central metal ion, higher is the stability of the complex. The order of oxidation state of metal ions in the given complex is $\mathrm{Co}^{3+}\gt\mathrm{Cu}^{2+}\gt\mathrm{Ag}^{+}$.

Asked in: MHT CET 2024 (11 May Shift 2)

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