Polysubstitution is a major drawback in

Benzyl bromide on reaction with magnesium in the presence of dry ether gives $'X'$. $'X'$ on reaction with ethanol gives $'Y'$. Then the compound $Y$ is

What is produced when toluene is heated with chlorine in the presence of light and in the absence of a halogen carrier?

$HBr$ reacts with $CH_2=CH-OCH_3$ at room temperature to give

In the following reaction $C_{6}H_{5}CH_{2}Br \xrightarrow[(ii)H_{3}O^{+}]{(i)Mg, \text{Ether}} X$
Product $X$ is

Consider all the structural isomers with molecular formula $C_5H_{11}Br$. They are separately treated with $KOH$ $(aq)$ to give respective substitution products, without any rearrangement. The number of products which can exhibit optical isomerism from these is . . . . . . .