What is a characteristic feature of a racemic mixture?

A racemic mixture is defined as an equimolar mixture of two enantiomers, which are molecules that are mirror images of each other but cannot be superimposed. This characteristic feature of being a 50:50 combination of enantiomers means that the optical activities of the two enantiomers effectively cancel each other out when mixed together.

As a result, while each enantiomer is optically active when isolated, the overall racemic mixture does not exhibit optical activity. This is due to the fact that the rotation produced by one enantiomer counteracts the rotation produced by the other, leading to a net rotation of zero. Thus, the correct characterization of a racemic mixture hinges on its composition of equal parts of both enantiomers, making the option that it is a 50:50 mixture of two enantiomers the most accurate representation.