When $50 \% d$ -form is mixed with $50 \%$ l form, a racemic mixture is obtained.
Hence, an equimolar mixture of the enantiomers (dextro or laevo forms) is called racemic mixture.
It is represented as $d l$ form or $\pm$ form and is optically inactive due to external compensation. Separation of racemic mixture into $d-$ and $l$ -forms is called resolution.