A reaction of cobalt (III) chloride and ethylenediamine in a 1:2 mole ratio generates two isomeric products A (violet coloured) and B (green coloured). A can show optical activity, but, B is optically inactive. What typeof isomers does A and B represent?

Analyzing the Isomers:

1. A (violet-colored) is optically active, meaning it can rotate plane-polarized light. Optical activity typically arises from chirality in molecules, which occurs when there is a non-superimposable mirror image (enantiomers). This suggests that A has a chiral center, and its geometry is such that it can exist as non-superimposable mirror images.
2. B (green-colored) is optically inactive, indicating it does not possess chirality and is likely a meso compound (which is achiral due to internal symmetry), or it may have a symmetrical arrangement of ligands that cancel out optical activity.

Type of Isomerism:

• Since A can show optical activity, it must involve chiral isomers, which means that A and B represent geometrical isomers. In geometrical isomerism, the same ligands are present, but their spatial arrangement leads to different physical properties (such as color or optical activity).

Conclusion:

• A and B represent geometrical isomers because they differ in their spatial arrangement, leading to different physical properties like color and optical activity.

Correct Answer: a: Geometrical Isomers.