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JEE Main 2026 Apr 6 Shift 1, Chemistry Q14: Structural Isomerism

JEE Main2026Apr 6, Shift 1Chemistry
Q.

Given below are two statements:

Statement-I: 2,6-diethylcyclohexanone and 6-methyl-2-n-propylcyclohexanone are metamers.

Statement-II: 2,2,6,6-tetramethylcyclohexanone exhibits keto-enol tautomerism.

In the light of the above statements, choose the correct answer from the options given below.

  1. A

    Both Statement-I and Statement-II are true.

  2. B

    Both Statement-I and Statement-II are false.

  3. C

    Statement-I is true but Statement-II is false.

  4. D

    Statement-I is false but Statement-II is true.

Solution

Statement-I: Metamers share the same molecular formula but differ in the distribution of carbons across the same functional group. 2,6-diethylcyclohexanone (two ethyl substituents flanking the carbonyl) and 6-methyl-2-n-propylcyclohexanone (methyl on one side, propyl on the other) both have molecular formula with the same carbonyl group, differing only in alkyl distribution. True.

Statement-II: Keto-enol tautomerism requires at least one -hydrogen. In 2,2,6,6-tetramethylcyclohexanone, both -carbons are fully substituted with methyl groups, leaving zero -H. Hence no tautomerism. False.

Statement-I is true, Statement-II is false.

Concept behind this question

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