Optical activity is measured by .................

Total possible stereoisomers from the given compound $CH_3-CH=CH-CH(OH)-CH(OH)-CH_3$ will be:

Which of the following compounds are optically active?
$(I)$ $1,1-$dimethyl$-4-$chlorocyclohexane
$(II)$ $4-$chlorocyclohex$-1-$ene
$(III)$ penta$-2,3-$diene

The following compound can exhibit:

If there is no rotation of plane polarised light by a compound in a specific solvent,though thought to be chiral,it may mean that

What are the optical isomers called that are optically active but are not mirror images of each other?