Which of the following compounds is chiral?

The process of conversion of the $d$-form of an optically active compound into its $l$-form or vice versa is known as ......

Lactic acid shows which type of 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 $2$.

Which among the following is $NOT$ a true statement regarding enantiomers?

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