The major product formed in the Friedel-Crafts acylation of chlorobenzene is $p-$chloroacetophenone. Identify the correct structure of the major product.

The reaction between chlorobenzene and chloral in the presence of concentrated sulphuric acid produces

The decreasing order of reactivity of the given compounds towards nucleophilic substitution with aqueous $NaOH$ is:
$(I)$ $1$-bromo-$3$-nitrobenzene
$(II)$ $1$-bromo-$2,4,6$-trinitrobenzene
$(III)$ $1$-bromo-$4$-nitrobenzene
$(IV)$ $1$-bromo-$2,4$-dinitrobenzene

Among the following,the reaction that proceeds through an electrophilic substitution is

Arrange the following compounds in increasing order of their dipole moment:
$(I)$ Toluene
$(II)$ $m$-Dichlorobenzene
$(III)$ $o$-Dichlorobenzene
$(IV)$ $p$-Dichlorobenzene

Which one of the following compounds is most reactive for $ArS_N2$ reaction?