Aromatic hydrocarbons mostly exhibit .......

Given the following structures:
$(I)$ $1,3,5-$trimethylbenzene (mesitylene)
$(II)$ $1,3-$dimethyl$-5-$methylenecyclohexa$-1,3-$diene
$(III)$ $1,3,5-$trimethylenecyclohexane
The enthalpy of hydrogenation of these compounds will be in the order as:

The order of stability of the aromatic hydrocarbons given below is:

The reaction $2 C_6H_6 + CH_2Cl_2 \xrightarrow{AlCl_3, \Delta} ?$ gives the major product:

The product obtained in the reaction of benzene with chlorine in the presence of ultraviolet light is ...... .

The correct structure of benzene was proposed by