Question

how shows optical active

Answer 1

One enantiomer of these chiral compounds is dextrorotatory; the other is levorotatory. To decide whether a compound should be optically active, we look for evidence that the molecules are chiral. The instrument with which optically active compounds are studied is a polarimeter, shown in the figure below.

Answer 2

optically active isomer have chiral molecule, molecular asymmetry, must be sp3, and centre of symmetry and plane of symmetry must be absent