Medium MCQ +4 / -1 PYQ · JEE Mains 2025

One mole of the octahedral complex compound $\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}_3$ gives 3 moles of ions on dissolution in water. One mole of the same complex reacts with excess of $\mathrm{AgNO}_3$ solution to yield two moles of $\mathrm{AgCl}_{(\mathrm{s})}$. The structure of the complex is:

  1. A $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2$ Correct answer
  2. B $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}\right] \cdot \mathrm{Cl}_2 \cdot \mathrm{NH}_3$
  3. C $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3 \mathrm{Cl}_3\right] \cdot 2 \mathrm{NH}_3$
  4. D $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right] \cdot \mathrm{Cl} \cdot \mathrm{NH}_3$

Solution

<p>$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2 \rightarrow \underbrace{\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right]^{2+}(\text { aq. })+2 \mathrm{Cl}^{-} \text {(aq.) }}_{3 \text { ions in water }}$</p> <p>$$\begin{gathered} \left.\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2 \text { (aq.) }\right)+2 \mathrm{AgNO}_3 \text { (aq.) } \rightarrow \\ {\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right]\left(\mathrm{NO}_3\right)_2(\text { aq. })+2 \mathrm{AgCl}(\mathrm{~s})} \end{gathered}$$</p>

About this question

Subject: Chemistry · Chapter: Coordination Compounds · Topic: Ligands and Coordination Number

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