How many structural isomers does pentane (C5H12) have, including pentane itself?
Answer and explanation
Correct answer: C. 3
- Step 1: Straight chain: pentane. Step 2. One branch: 2-methylbutane. Step 3. Two methyl branches on one carbon: 2,2-dimethylpropane. That gives 3 isomers. Answer: 3. Why not the others: 2 is the number of isomers of butane; 4 and 5 count repeated structures such as 3-methylbutane (the same as 2-methylbutane).
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