Liquid hydrocarbons can be converted to a mixture of gaseous hydrocarbons by :

$2,3$-Dimethyl-$2$-butene can be prepared by heated which of the following compounds with a strong acid?

The compound ${\mathrm{C}}_7{\mathrm{H}}_8$ undergoes the following reactions:

${\mathrm{C}}_7{\mathrm{H}}_8\stackrel{3{\mathrm{Cl}}_2/\mathrm{\Delta }}{⟶}\mathrm{A}\stackrel{{\mathrm{Br}}_2/\mathrm{Fe}}{\to }\mathrm{B}\stackrel{\mathrm{Zn}/\mathrm{HCl}}{\to }\mathrm{C}$

The product $\text{'}\mathrm{C}\text{'}$ is

Given:

The enthalpy of the hydrogenation of these compounds will be in the order as :-

Predict the product $\text{'}\mathrm{C}\text{'}$ obtained in the following reaction of $1$-butyne :

${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{C}\equiv \mathrm{CH}+\mathrm{HCl}\to \mathrm{B}\stackrel{\mathrm{HI}}{\to }\mathrm{C}$

The order of decreasing reactivity towards an electrophilic reagent, for the following
(A) Benzene
(B) Toluene
(C) Chlorobenzene and
(D) Phenol

would be