Question

Which of the following rotates the plane of plane polarised light?

• A. Compound which is having enantiomeric excess
• B. Diastereomers
• C. Racemic mixture
• D. None

Answer 1

Answer: (A)

Compound which is having enantiomeric excess

Compound which is having enantiomeric excess rotate the plane polarised light.
For example, a $50:50$ mixture of two enantiomers or a racemic mixture will not rotate plane polarised light and is optically inactive. A mixture that contains one enantiomer excess, however, will display a net plane of polarisation in the direction characteristic of the enantiomer that is in excess.
Hence option A is correct.