What is the possible number of optical isomers for a compound containing $2$ dissimilar asymmetric carbon atoms?

Find the enantiomers of the structures in Column-$(I)$ from Column-$(II)$.

Column-$(I)$	Column-$(II)$
$(A)$ $C_2H_5-C(CH_3)(OH)-H$	$(p)$ $Cl-C(Br)(I)-H$
$(B)$ $Br-C(Cl)(I)-H$	$(q)$ $OH-C(CH_3)(C_2H_5)-H$
	$(r)$ $H_5C_2-C(OH)(CH_3)-H$
	$(s)$ $Cl-C(I)(Br)-H$

Which of the following compounds exhibits optical isomerism?

The correct statement$(s)$ about the compound $H_3C-CH(OH)-CH=CH-CH(OH)-CH_3$ $(X)$ is(are):
$(A)$ The total number of stereoisomers possible for $X$ is $6$.
$(B)$ The total number of diastereomers possible for $X$ is $3$.
$(C)$ If the stereochemistry about the double bond in $X$ is trans,the number of enantiomers possible for $X$ is $4$.
$(D)$ If the stereochemistry about the double bond in $X$ is cis,the number of enantiomers possible for $X$ is $2$.

Optically active isomers that are not mirror images of each other are called:

Which one of the following is an optically active compound?