Explain/Define the following terms:
$(i)$ Laevorotatory isomer
$(ii)$ Optical isomers

(N/A) $(i)$ Laevorotatory isomer:
$A$ compound is called laevorotatory $(l)$ or $(-)$ if its solution rotates the plane of plane-polarized light to the left (anticlockwise direction). The $l$-rotation is indicated by placing a $(-)$ sign before the value of the angle of rotation.
$(ii)$ Optical isomers:
The $(+)$ and $(-)$ isomers of a compound are known as optical isomers,and this phenomenon is called optical isomerism.