See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Concept: Structural isomers (also called constitutional isomers) are compounds with the same molecular formula but different connectivity of atoms. C6H14 is a saturated alkane (CnH2n+2, n=6), so we enumerate all possible carbon skeleton arrangements. Step 1: Identify the degree of unsaturation. DoU = (2×6 + 2 - 14)/2 = 0, confirming it is a fully saturated acyclic alkane. Step 2: Systematically enumerate all distinct carbon skeletons for hexane (6 carbons). Isomer 1 – n-hexane: straight chain of 6 carbons. CH3-CH2-CH2-CH2-CH2-CH3 Isomer 2 – 2-methylpentane: 5-carbon main chain with a methyl branch at C2. CH3-CH(CH3)-CH2-CH2-CH3 Isomer 3 – 3-methylpentane: 5-carbon main chain with a methyl branch at C3. CH3-CH2-CH(CH3)-CH2-CH3 Isomer 4 – 2,2-dimethylbutane: 4-carbon main chain with two methyl groups at C2. CH3-C(CH3)2-CH2-CH3 Isomer 5 – 2,3-dimethylbutane: 4-carbon main chain with methyl groups at C2 and C3. CH3-CH(CH3)-CH(CH3)-CH3 Step 3: Check for any additional isomers. A 3-carbon main chain would require three methyl branches totaling 6 carbons, but 3 + 3 = 6 with three methyls on propane is neopentane-like; however, attaching three methyls to propane gives C3 + 3C = C6, which would be 2,2-dimethylpropane... but that is C5H12, not C6H14. No valid additional skeletons exist. Step 4: Count confirmed distinct structures: n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane = 5 total. Therefore, the correct answer is 5.