In the presence of peroxide,styrene reacts with $HBr$ to give $X$. When $X$ is reacted with magnesium in dry ether followed by $CO_2$ and hydrolysis,it gives $Y$. Treatment of $Y$ with $PCl_5$ and then with $H_2, Pd-BaSO_4$ gives $Z$. What is $Z$?

Which of the following reactions is not possible?

Identify the number of $\alpha$-Hydrogen atoms in the given compound.

$p$-cresol reacts with chloroform in an alkaline medium to give compound $A$,which adds hydrogen cyanide to form compound $B$. The latter,on acidic hydrolysis,gives a chiral carboxylic acid. The structure of the carboxylic acid is:

Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions.
$(i)$ Ethanal,Propanal,Propanone,Butanone.
$(ii)$ Benzaldehyde,$p-$Tolualdehyde,$p-$Nitrobenzaldehyde,Acetophenone.
Hint: Consider steric effect and electronic effect.

Which of the following compounds is reduced to the corresponding hydrocarbon by $Zn-Hg$ and concentrated $HCl$?