NEET Chemistry Question (2026) — Solution

Step-by-step solution

1. Identify the longest continuous carbon chain: The longest chain in the given structure contains 7 carbon atoms. Therefore, the parent alkane is heptane. 2. Identify the substituents: There is an ethyl group ( -CH _2 CH _3) and a methyl group ( -CH _3) attached to the main chain. 3. Number the carbon chain: - Numbering from left to right gives the substituents at positions 3 (ethyl) and 5 (methyl). - Numbering from right to left gives the substituents at positions 3 (methyl) and 5 (ethyl). 4. Apply the alphabetical rule: When two different numbering schemes give the same set of locants (3, 5), the lower number is assigned to the substituent that is cited first alphabetically. Since 'ethyl' comes before 'methyl', the ethyl group must get the lower number (3). 5. Formulate the name: Combining these parts, the correct IUPAC name is 3-ethyl-5-methylheptane. Answer: 3-ethyl-5-methylheptane