For the given compound $X$, the total number of optically active stereoisomers is. . . . . . .
$2$-chlorobutane $+\mathrm{Cl}_2 \rightarrow \mathrm{C}_4 \mathrm{H}_8 \mathrm{Cl}_2$ (isomers)
Total number of optically active isomers shown by $\mathrm{C}_4 \mathrm{H}_8 \mathrm{Cl}_2$, obtained in the above reaction is......................
Total number of substituent present in the above compound
Which of the following is $D-$ isomer
Which of the following compounds is chiral ?