Question

What is a racemic mixture ? Give an example.

Answer 1

A mixture containing two enantiomers in equal proportions will have zero optical rotation, as the rotation due to one isomer will be cancelled by the rotation due to the other isomer. Such a mixture is known as racemic mixture or racemic modification.
A racemic mixture is represented by prefixing $dl$ or (±) before the name, for example (±) butan-2-ol