Which of the following is used as a catalyst in the manufacture of toluene from benzene with $CH_3Cl$?

What is the expected order of reactivity of the following compounds in electrophilic chlorination $(Cl_2 + FeCl_3)$? (more reactive $ > $ less reactive)
$I: C_6H_5CH_2CO_2H$
$II: C_6H_5N(CH_3)_2$
$III: C_6H_5OCOCH_3$
$IV: C_6H_5CCl_3$

In the Friedel-Crafts reaction,anhydrous $AlCl_3$ is used because...

The order of reactivity of the following compounds towards electrophilic substitution will be - [where $\phi = C_6H_5$]:
$I. \phi-CH_3$
$II. \phi-CH_2-CH_3$
$III. \phi-CH(CH_3)_2$
$IV. \phi-C(CH_3)_3$

Write about the nitration reaction of benzene.

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