Question

what is optically active compounds​

Answer 1

Compounds that rotate the plane of polarized light are termed optically active. Each enantiomer of a stereoisomeric pair is optically active and has an equal but opposite-in-sign specific rotation. ... For example, the lactic acid and carvone enantiomers discussed earlier have the following specific rotations.

Answer 2

A compound capable of optical rotation is said to be optically active. All pure chiral compounds are optically active.

eg: (R)-Lactic acid (1) is chiral and rotates the plane of plane-polarized light. Thus, 1 is optically active.