Q.Write IUPAC name of the compound drawn as structure iii. — a benzene ring with -OH and -NO₂ on adjacent (ortho) carbons:

The hydroxyl derivative of benzene is universally called phenol; its fully systematic IUPAC name is benzenol, though the shorter common name 'phenol' is itself IUPAC-accepted and used throughout in practice. When a second substituent is present, the common-name system uses the prefixes ortho (1,2-), meta (1,3-) and para (1,4-) to describe its relative ring position (e.g. o-cresol), while the IUPAC system instead uses plain numerical locants counted from the -OH-bearing carbon, which is always numbered C-1 (e.g. o-cresol becomes 2-methylphenol). The same locant convention extends to d …