Which of the following types of isomerism is shown by pentanone?

The process of separation of a racemic mixture into $d$ and $l$ enantiomers is called .............

Which of the following pairs are not diastereomers?

The molecules represented by the two structures shown in the image are:

Which of the following molecules is not chiral?

$A$ pair of stereoisomers might be classified in various ways. Which of the following statements are true with respect to pairs of stereoisomers?
$a$. They might be configurational isomers
$b$. They might be diastereomers
$c$. They might be constitutional isomers
$d$. They might be tautomers
$e$. They might be conformational isomers
$f$. They might be enantiomers
$g$. They might be positional isomers