Questions: Which of the following has the lowest heat of combustion ( kJ / mol) ? Cyclopentane Methylcyclopentane Methylcyclohexane Cycloheptane Methylcycloheptane

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The heat of combustion is the energy released when a compound undergoes complete combustion with oxygen. It is typically measured in kilojoules per mole (kJ/mol). Generally, the more stable a compound, the lower its heat of combustion.

The compounds listed are cycloalkanes and methyl-substituted cycloalkanes. The heat of combustion is influenced by the number of carbon atoms and the degree of substitution. More carbon atoms and more branching typically lead to higher heats of combustion.

1. Cyclopentane: A five-membered ring with no substitutions.
2. Methylcyclopentane: A five-membered ring with one methyl group.
3. Methylcyclohexane: A six-membered ring with one methyl group.
4. Cycloheptane: A seven-membered ring with no substitutions.
5. Methylcycloheptane: A seven-membered ring with one methyl group.

Cyclopentane, having the smallest ring and no substitutions, is expected to have the lowest heat of combustion due to its relatively lower number of carbon atoms and lack of additional substituents.

Final Answer