Question

Which of the following molecules is/are optically active ?

• A. I, III only
• B. II, III only
• C. I, II only
• D. I, II and III

Answer 1

The correct option is D I, II and III

Compounds having non-superimposable mirror images are known as chiral compounds

Generally, compound having chiral centre and lacks plane and centre of symmetry are optically active.
Here, all the compounds have non-superimposable mirror images and are chiral.

Both structure I and II has chiral carbon and lacks plane of symmetry and centre of symmetry.

In structure III, one of the $C$ has two identical groups ($Cl$), so it is not a chiral centre but there is another carbon centre which is chiral and hence molecule becomes optically active.

Hence, (d) is correct.