Given below are two statements: Statement I: $[\mathrm{Co}(\mathrm{NH}{}_3){}_6]{}^{3+}$ is a homoleptic complex whereas $[\mathrm{Co}(\mathrm{NH}{}_3){}_4\mathrm{Cl}{}_2]{}^{+}$ is a heteroleptic complex. Statement II: Complex $[\mathrm{Co}(\mathrm{NH}{}_3){}_6]{}^{3+}$ has one kind of ligands but $[\mathrm{Co}(\mathrm{NH}{}_3){}_4\mathrm{Cl}{}_2]{}^{+}$ has more than one kind of ligands. In the light of the above statements, choose the correct answer from the options given below:

Solution & Explanation

\textbf{Answer:} (D) Both Statement I and Statement II are true. \textbf{Solution:} A homoleptic complex has only one kind of ligand; a heteroleptic complex has two or more kinds. $[\mathrm{Co}(\mathrm{NH}{}_3){}_6]{}^{3+}$ is bound only by six identical ammine ligands → homoleptic. $[\mathrm{Co}(\mathrm{NH}{}_3){}_4\mathrm{Cl}{}_2]{}^{+}$ has both ammine and chlorido ligands (two kinds) → heteroleptic. So Statement I is true. Statement II simply restates the defining reason — one kind of ligand vs more than one kind — which is exactly the criterion that makes the first complex homoleptic and the second heteroleptic. So Statement II is true and is the correct explanation of Statement I. Hence both statements are true, option (D).