Which of the following has the highest heat of hydrogenation?

Which of the following reactions are not feasible?
$I$. $CH_3CH=CH_2 \xrightarrow{HCl, (C_6H_5CO)_2O_2} CH_3CH_2CH_2Cl$
$II$. $C_6H_6 + CH_3CH_2CH_2Cl \xrightarrow{AlCl_3} C_6H_5CH(CH_3)_2$
$III$. $CH_3CHClCH_2Cl \xrightarrow{KOH, \Delta} CH_3C \equiv CH$
$IV$. $CH_3CH=CHCH_3 \xrightarrow{KMnO_4 / H^+} CH_3COOH$

Compound $X$ of molecular formula $C_4H_6$ takes up one equivalent of hydrogen in the presence of $Pt$ to form another compound $Y$,which on ozonolysis gives only ethanoic acid. The compound $X$ can be:

What is the major product of the following $E2$ reaction?

Addition of a mineral acid to an olefin bond leads to a major product. Identify it.

The major product $'A'$ of the following given reaction has $......\,sp^2$ hybridized carbon atoms.
$2,7-\text{Dimethyl}-2,6-\text{octadiene} \xrightarrow{H^{+}} A \text{ (Major Product)}$