See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the principal characteristic group. The molecule contains an aldehyde (–CHO) functional group, so the parent chain must end at the aldehyde carbon, which is C1. Step 2: Find the longest continuous carbon chain that includes the aldehyde carbon. Starting from the CHO carbon: C1(CHO)–C2H2–C3H(with ethyl branch)–C4H2–C5H2–C6H2–C7H3. This gives a 7-carbon chain, so the parent name is heptanal. Step 3: Identify substituents. At C3 there is a two-carbon branch (–CH2CH3), which is an ethyl group. Step 4: Number the chain. The aldehyde carbon is C1 (fixed by IUPAC rules for aldehydes). The ethyl substituent is located at C3. Step 5: Assemble the name. Parent chain = heptanal; substituent = 3-ethyl. Full IUPAC name = 3-ethylheptanal. Step 6: Verify. No other chain of 7 or more carbons includes the aldehyde carbon while placing the substituent at a lower locant, confirming the name is correct. Therefore, the correct answer is 3-ethylheptanal.