JEE Main · 2026 · 21 Jan 2026 · Shift 1 · General Organic Chemistry

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Identify correct statement from the following:

A. Propanal and propanone are functional isomers.
B. Ethoxyethane and methoxypropane are metamers.
C. But-2-ene shows optical isomerism.
D. But-1-ene and but-2-ene are functional isomers.
E. Pentane and 2, 2-dimethyl propane are chain isomers.

Choose the correct answer from the options given below:

(A)B, C and D only
(B)A, B and C only
(C)A, B and E only✓ Correct
(D)C, D and E only

Answer: (C)

Solution

Propanal and propanone share the formula C

_{3}

_{6}

O but differ in functional group, aldehyde against ketone, so they are functional isomers and statement A holds. Ethoxyethane, C

_{2}

_{5}

_{2}

_{5}

, and methoxypropane, CH

_{3}

_{3}

_{7}

, are both ethers of formula C

_{4}

_{10}

O differing in the alkyl groups flanking oxygen, so they are metamers and statement B holds. But-2-ene has no carbon bearing four different groups, so it shows geometrical rather than optical isomerism, and statement C fails. But-1-ene and but-2-ene are both alkenes differing only in the position of the double bond, making them positional and not functional isomers, so statement D fails. Pentane and 2,2-dimethylpropane share C

_{5}

_{12}

with different skeletons, so they are chain isomers and statement E holds. The correct statements are A, B and E only.

Structure 2,2-dimethylpropane — 2,2-dimethylpropane

JEE Main · 2026 · 21 Jan 2026 · Shift 1 · Single correct option

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JEE Main · 2026 · 21 Jan 2026 · Shift 1 · General Organic Chemistry

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