Question

Find out the total number of cyclic isomers of c6h12 which are optically active

Answer 1

Still you need to remember that isomers are those groups having same molecular formula and different structural formula.

Thus total number of isomers are 3.

Consider the breakdown below.

Cyclohexane is normally not active.  

Ethylcyclopentane is normally not active.  

Dimethylcyclobutanes has only 1 active isomer.  

Ethylcyclobutane is normally not active  

Trimethylcyclopropanes has only 1 active isomer.  

Ethylmethylcyclopropane has 2 pairs of enantiomers.  

Propyl and isopropylcyclopropanes is normally not active

Answer 2

the answer should be 6.

as the marked structures have a chiral carbon.