Separating of $d$ and $l$ enantiomorphs from a racemic mixture is called

The maximum number of stereoisomers that could exist for the compound below ?

Number of optically active isomer is/are

Which is optically active ?

Which of the following statements is not true about enantiomers

Compound$(s)$ that on hydrogenation produce$(s)$ optically inactive compound$(s)$ is (are)