Product $(B)$ is

Match the following reactions in List-$I$ with their products in List-$II$:

List-$I$	List-$II$
$A$. The reaction of $1,6$-dibromohexane with $Zn$.	$i$. $H_3C-C \equiv CH$
$B$. Reaction of ethanol with concentrated $H_2SO_4$ at $443 \ K$.	$ii$. $H_2C=CH_2$
$C$. Major product in the reaction of propene with $HBr$ in the presence of benzoyl peroxide.	$iii$. $CH_3-CH_2-CH_2-Br$
$D$. The reaction of $1,1$-dibromopropane with $NaNH_2$ at $433 \ K$.	$iv$. Cyclohexane

Arrange the compounds $I$,$II$,and $III$ in decreasing order of their heats of combustion.

What is the major product of the following reaction?

Arrange the following compounds in decreasing order of acidic character of $C-H$ bonds.
$CH_2=CH_2, CH_3-CH_3, C_6H_6, CH\equiv CH$

The compound with molecular formula $C_6H_6$,which gives only one monobromo derivative and takes up four moles of hydrogen per mole for complete hydrogenation,has $................\pi$ electrons.