The number of stereoisomers of the compound $CH_3CHBrCHBrCOOH$ is

$A$ molecule is divided into two identical halves and contains $n$ asymmetric carbon atoms. What is the total number of stereoisomers?

Number of optical isomers possible for $2$-chlorobutane is:

In the reaction sequence shown below,determine the total number of stereoisomers formed as the final product $D$. The starting material is $CH_3-CD(CH_3)-C \equiv C-CO-CH_3$. The reaction $A$ is $LiAlH_4$ (or similar reducing agent to reduce the alkyne to a cis-alkene),$C$ is the cis-isomer,and the final step is the addition of $Br_2/CCl_4$.

The number of optical isomers possible for $3,4-$dichloropentan$-2-$ol is

Which of the following compounds is optically active?