The reaction of vinyl chloride with $HCl$ yields ...... .

What is the major product $Z$ in the given reaction sequence?
$(CH_3)_2 C=O \xrightarrow[(2) H_3O^{+}]{\text{(1) } C_2H_5MgBr} X$
$i) SOCl_2$ $\xrightarrow[\Delta]{\text{ii) } CH_3ONa} Y$ $\xrightarrow[\text{Peroxide}]{HBr} Z$

An alkene $X$ $(C_4H_8)$ on reaction with $HBr$ gave $Y$ $(C_4H_9Br)$. Reaction of $Y$ with benzene in the presence of anhydrous $AlCl_3$ gave $Z$,which is resistant to oxidation with $KMnO_4-KOH$. What are $X, Y, Z$ respectively?

When $tert$-butyl bromide is heated with silver fluoride,the major product obtained is:

The $S_{N}2$ reaction mechanism proceeds through ........

Which is the major product expected from the following $S_{N}2$ reaction?