Which of the following possesses the highest melting point?

Assertion : $p-$nitroacetophenone $(p-O_2N-C_6H_4-COCH_3)$ is prepared by Friedel-Crafts acylation of nitrobenzene.
Reason : Nitrobenzene easily undergoes electrophilic substitution reaction.

Which catalyst is used in the Friedel-Crafts reaction?

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:

Heating chlorobenzene with $NaOH$ at $300\,^oC$ under pressure yields ...........

Assertion : Cyanide $(CN^{-})$ is a strong nucleophile.
Reason : Benzonitrile is prepared by the reaction of chlorobenzene with potassium cyanide.