See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the parent chain/functional group: The structure shows a benzene ring bearing an aldehyde group (-CHO), so the parent name is benzaldehyde. The carbon bearing the CHO is C-1 by IUPAC convention. Step 2 - Identify substituents and their positions: Going around the ring from C-1 (CHO), there is a chlorine (Cl) directly adjacent at C-2 (ortho position), and a bromine (Br) at C-4 (para position relative to CHO). Step 3 - Apply IUPAC numbering: The principal characteristic group (CHO) receives the lowest possible locant, which is C-1. Numbering proceeds to give the substituents the lowest set of locants. Cl at C-2 and Br at C-4 satisfy this requirement. Step 4 - Construct the name: Substituents are listed alphabetically before the parent name: bromo (Br, position 4) comes before chloro (Cl, position 2) alphabetically. Thus the name is 4-bromo-2-chlorobenzaldehyde. Step 5 - Why no other name applies: The CHO is the principal group and defines C-1; the ortho-Cl is therefore at C-2, and the para-Br is at C-4, leaving no ambiguity in numbering. Therefore, the correct answer is 4-bromo-2-chlorobenzaldehyde.