Identify the number of complexes that are optically active $$ \begin{aligned} & {\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+} ;\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right]^{+} ;} \\ & {\left[\mathrm{CoCl}_2(\mathrm{en})_2\right] ;\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3\left(\mathrm{NO}_2\right)_3\right]} \end{aligned} $$

• A

  0
• B

  1
• Correct answer
  C

  2
• D

  3

Solution

Complex $\mathrm{Co}(\mathrm{en})_3$ is optically inactive.
$$ \text { From is optically active. } $$

Hence, the correct answer is option: 'C'.