The reaction of benzene with $CO$ and $HCl$ in the presence of anhydrous $AlCl_3$ gives :

Which of the following molecules,in pure form,is (are) unstable at room temperature?
$(A)$ $1,3-$cyclohexadiene
$(B)$ Cyclobutadiene
$(C)$ Cyclopentadienone
$(D)$ Cycloheptatrienone (Tropone)

Which of the following compounds undergoes the Friedel-Crafts reaction?

The enthalpy of hydrogenation of benzene is $\Delta H_1$ and for cyclohexene is $\Delta H_2$. Then the resonance energy of benzene is:

The most common type of reaction in aromatic compounds is

Which xylene is most easily sulphonated?