Give some examples of optical isomerism exhibited by complexes of coordination number $6$.

$\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5\mathrm{Br}\right]{\mathrm{SO}}_4$ and $\left[(\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5{\mathrm{SO}}_4\right]\mathrm{Br}$ show _____ isomerism.

$\mathrm{A}:$Solvate

$\mathrm{B}:$Ionisation

$\mathrm{C}:$Linkage

Enter your correct answer as $\mathrm{A}, \mathrm{B} \mathrm{or} \mathrm{C}$.

Write the possible isomers of the following compounds.

(i) $\left[\mathrm{Cr}{\left(\mathrm{en}\right)}_3\right]{\mathrm{Cl}}_3$ and  $\left[\mathrm{Cr}{\left(\mathrm{en}\right)}_2{\mathrm{Cl}}_2\right]\mathrm{Cl}$.