When petroleum is heated,the vapours contain mainly:

Which of the following substituted benzene derivatives would furnish three isomers in significant amount when one more substituent is introduced:

Methylcyclopentane $\xrightarrow{Br_2/hv} \mathop{Major}\limits_{(X)}$ $\xrightarrow[KOH/\Delta]{Alcoholic} \mathop{Major}\limits_{(Y)}$ $\xrightarrow[Peroxide]{HBr} \mathop{Major}\limits_{(Z)}$
Major final product $(Z)$ is

In the combustion of hydrocarbons,$\Delta H$ is

The maximum number of bromine atoms present in the final product $P$ upon complete bromination is

The petrol having octane number $80$ has