The function of anhydrous $AlCl_3$ in the Friedel-Crafts reaction is to ........ .

$1$-$Chloro$-$4$-$nitrobenzene$,$1$-$Chloro$-$2,4$-$dinitrobenzene$ and $1$-$Chloro$-$2,4,6$-$trinitrobenzene$ are transformed to corresponding phenols with the reagents $X$,$Y$,$Z$ respectively. What are $X$,$Y$,$Z$?

Which of the following statements are correct?
$A$. The $C-Cl$ bond in chlorobenzene is shorter than in chloromethane.
$B$. It is more difficult to replace chlorine from chlorobenzene than from benzyl chloride.
$C$. The $C-Cl$ bond in chlorobenzene has some double bond character.
$D$. Chlorobenzene on chlorination gives $m$-dichlorobenzene.

The decreasing order of reactivity of $meta$-nitro-bromobenzene $(I)$,$2,4,6$-trinitro-bromobenzene $(II)$,$para$-nitro-bromobenzene $(III)$,and $2,4$-dinitro-bromobenzene $(IV)$ towards $HO^-$ ions is:

Which of the following possesses the highest melting point?

Which among the following statements is true about the reactivity of haloarenes towards nucleophilic substitution reactions?
$1$. Haloarenes are very reactive towards nucleophilic substitution reaction.
$2$. In haloarenes,the $C-X$ bond acquires partial double bond character.
$3$. The $C-X$ bond in haloarenes is longer than the $C-X$ bond in haloalkanes.
$4$. In haloarenes,the phenyl cation formed as a result of self-ionisation is stable.