Exams › JEE Main › Chemistry
Consider two statements. Statement I: The presence of the weaker pi bond makes alkenes less stable (more reactive) than alkanes. Statement II: The strength of a carbon-carbon double bond is greater than that of a carbon-carbon single bond. Choose the correct option.
- Both Statement I and Statement II are correct.
- Both Statement I and Statement II are incorrect.
- Statement I is correct but Statement II is incorrect.
- Statement I is incorrect but Statement II is correct.
Correct answer: Both Statement I and Statement II are correct.
Solution
An alkene's C=C contains a sigma and a pi bond. The pi bond is weaker and exposed, making alkenes more reactive (less kinetically inert) than alkanes - Statement I is correct. However the overall double bond energy is greater than a single bond because it has two components; a C=C bond (~611 kJ/mol) is stronger than a C-C bond (~347 kJ/mol), though not twice as strong - Statement II is correct. The pi bond being weaker than the sigma bond is consistent with both statements.
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