Isomer Count
Easychemistry
Number of structural isomers of C5H12 (pentane) is:
Select the correct option:
Solution
Incorrect! Answer:
3
- Formula: C5H12 follows the general formula for alkanes (CnH2n+2).
- Isomer 1 (Normal): n-pentane (a continuous chain of 5 carbons).
- Isomer 2 (Iso): 2-methylbutane (a 4-carbon chain with a methyl branch on the 2nd carbon).
- Isomer 3 (Neo): 2,2-dimethylpropane (a central carbon with 4 methyl groups attached; also conceptually a 3-carbon chain with two branches).
- Total: There are exactly 3 structural isomers. Beyond C5, the number of possible isomers increases rapidly.
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About This Question
- Subject
- chemistry
- Chapter
- hydrocarbons
- Topic
- isomer count
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
3
- Formula: C5H12 follows the general formula for alkanes (CnH2n+2).
- Isomer 1 (Normal): n-pentane (a continuous chain of 5 carbons).
- Isomer 2 (Iso): 2-methylbutane (a 4-carbon chain with a methyl branch on the 2nd carbon).
- Isomer 3 (Neo): 2,2-dimethylpropane (a central carbon with 4 methyl groups attached; also conceptually a 3-carbon chain with two branches).
- Total: There are exactly 3 structural isomers. Beyond C5, the number of possible isomers increases rapidly.
This easy difficulty chemistry question is from the chapter hydrocarbons, covering the topic of isomer count. It appeared in the 2025 exam.
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