Chemistry - Coordination Chemistry Question with Solution | TestHub

The complex is $\mathrm{CoClBr}\cdot 5{\mathrm{NH}}_3$.

Isomer I: ${\mathrm{Cl}}^{-}$ is in the coordination sphere. Formula: $[\mathrm{Co}({\mathrm{NH}}_3{)}_5\mathrm{Cl}]\mathrm{Br}$.

Isomer II: ${\mathrm{Br}}^{-}$ is in the coordination sphere. Formula: $[\mathrm{Co}({\mathrm{NH}}_3{)}_5\mathrm{Br}]\mathrm{Cl}$.

A. Both are ionization isomers as they differ in the counter ion and a ligand inside the coordination sphere. (Correct statement)

B. Both isomers have the general formula $[{\mathrm{MA}}_5\mathrm{B}]$, which do not show geometrical isomerism. (Correct statement)

C. Primary valency is satisfied by the counter ions. For Isomer I, it's ${\mathrm{Br}}^{-}$. For Isomer II, it's ${\mathrm{Cl}}^{-}$. These are different ions. (Incorrect statement, but the question asks for the incorrect statement among the options, so this option is a correct choice if it were phrased as "Primary valency of both isomers is satisfied by different ions.")

D. Isomer I is $[\mathrm{Co}({\mathrm{NH}}_3{)}_5\mathrm{Cl}]\mathrm{Br}$. It has ${\mathrm{Br}}^{-}$ as a counter ion. Reaction with ${\mathrm{AgNO}}_3$ (aq.) will produce $\mathrm{AgBr}$ (pale yellow precipitate), not a white precipitate. Therefore, this statement is incorrect.

The incorrect statement is D.