Question

In lactic acid, a methyl group, a hydroxy group and a carboxylic group are attached to a central carbon atom shows optical activity due to the molecular geometry at:

• A. C - atom of methyl group
• B. C - atom of carboxylic group
• C. central carbon atom
• D. O - atom of hydroxy group

Answer 1

Answer: (C)

central carbon atom

The optical activity is shown by only those compound which has asymmetric carbon atom. In lactic acid central carbon atom is asymmetric carbon thus the optical activity of lactic acid is due to a central carbon atom.

An asymmetric carbon is a carbon at which four different groups are attached.