(N/A) Rules for nomenclature of aryl halides:
$(i)$ For monohalogen derivatives of benzene,the common and $IUPAC$ names are the same. In the $IUPAC$ system,prefixes $ortho- (o-)$,$meta- (m-)$,and $para- (p-)$ are replaced by $1,2-$,$1,3-$,and $1,4-$ respectively.
$(ii)$ If more than two halogen atoms are present in the ring,the $IUPAC$ system is used by numbering the ring positions $1, 2, 3, 4, 5, 6$ and using prefixes like $tri-$,$tetra-$,etc.
$(b)$ Examples:
| Structure | Common Name | $IUPAC$ Name |
| :--- | :--- | :--- |
| $C_6H_5Br$ | Bromobenzene | Bromobenzene |
| $C_6H_4Br_2$ $(o-)$ | $o$-Dibromobenzene | $1,2$-Dibromobenzene |
| $C_6H_4Br_2$ $(m-)$ | $m$-Dibromobenzene | $1,3$-Dibromobenzene |
| $C_6H_4Br_2$ $(p-)$ | $p$-Dibromobenzene | $1,4$-Dibromobenzene |
| $C_6H_3Br_3$ $(1,3,5-)$ | sym-Tribromobenzene | $1,3,5$-Tribromobenzene |
| $C_6H_3Br_3$ $(1,2,4-)$ | - | $1,2,4$-Tribromobenzene |