In a mixture, two enantiomers are found to be present in $85 \%$ and $15 \%$ respectively. The enantiomeric excess $(ee)$ is (in $\%$)

What is the number of chiral carbon atoms present in $2-$chloro$-3,4-$dimethylhexane?

What is the number of optically active isomers for the compound with the molecular formula $C_7H_{16}$?

An aqueous solution containing compounds $A$ and $B$ shows optical activity. $A$ and $B$ are stereoisomers. Which of the following possibilities cannot be correct?

Non-superimposable mirror images are called.........

Which one among the following cannot exhibit enantiomerism?