AIIMS2019Chemistry-Organic Chemistry

AIIMS 2019 Chemistry Tautomerism Assertion Reason Question

Type: Assertion Reason-conceptual-Medium-Class 11

Assertion: Enol form of cyclohex2x^{-2},⁴⁻diene1e^{-1} one is more stable than its keto form. Reason: Keto form contains α-hydrogen atoms.

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Correct Answer

Option B

Detailed Explanation

The assertion is true because the enol form of cyclohex-2,4-diene is stabilized by intramolecular hydrogen bonding and resonance, making it more stable than the keto form. However, the reason is false; while the keto form does contain α-hydrogens, their presence does not directly explain the stability of the enol form. Option A is incorrect because the reason does not correctly explain the assertion, while option C is incorrect as both statements are true. Option D is incorrect since the assertion is indeed true.

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