Are all $ortho$ and $para$ directing groups activators? Give examples.

Predict the product of the following reaction sequence:
$1$. Benzene + $CH_3CH_2CH_2COCl / AlCl_3$
$2$. $Zn(Hg), HCl$
$3$. $Br_2, FeBr_3$

Which of the following statements are correct with respect to benzene?
$(i)$ It forms triozonide with $O_3$.
$(ii)$ It is non-planar.
$(iii)$ It forms only one monosubstituted product with $CH_3COCl$ in the presence of anhydrous $AlCl_3$.
$(iv)$ It forms hexachlorobenzene on heating with $Cl_2$ under photochemical conditions.

Which one of these is not true for benzene?

Explain the mechanism for the nitration of benzene.

Find the decreasing order of reactivity towards electrophilic substitution reaction for the following compounds:
$I$: Toluene $(C_6H_5CH_3)$
$II$: Benzene $(C_6H_6)$
$III$: Anisole $(C_6H_5OCH_3)$
$IV$: Trifluoromethylbenzene $(C_6H_5CF_3)$