The following compounds are identical with respect to:

According to $Cahn-Ingold-Prelog$ sequence rules,the correct order of priority for the given groups is

The compounds $(X)$ and $(Y)$ are formed by replacing $H_a$ with $D$ (while keeping $H_b$ as $H$) and replacing $H_b$ with $D$ (while keeping $H_a$ as $H$) respectively in the given molecule. What is the relationship between $(X)$ and $(Y)$?

The total number of stereoisomers formed by the given compound is:

Select the correct option for the following compounds.

The major product$(s)$ of the reaction is (are):