Most of the hydrocarbons from petroleum are obtained by

Consider the following reactions:
$(a)$ $CH_3-CH=CH_2 + HBr \rightarrow CH_3-CH(Br)-CH_3$
$(b)$ $CH_3-CH=CH_2 + HBr \xrightarrow{Peroxide} CH_3-CH_2-CH_2Br$
$(c)$ $CH_4 + Cl_2 \xrightarrow{hv} CH_3Cl + HCl$
Which of these reactions proceed via a free radical mechanism?

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

Reactant $(A)$ can be

The correct order of heat of hydrogenation of the given molecules is:

Product $A$ of the above reaction is