Given below are two statements. Statement I : The dipole moment of \(\stackrel{4}{\mathrm{CH}}-\stackrel{3}{\mathrm{CH}}=\stackrel{2}{\mathrm{CH}}-\stackrel{1}{\mathrm{CH}}=\mathrm{O}\) is greater than (see structure) Statement II: \(\mathbf{C}_{\mathbf{1}}-\mathbf{C}_{\mathbf{2}}\) bond length of (see structure) is greater than \(\mathrm{C}_{1}-\mathrm{C}_{2}\) bond length of (see structure) In the light of the above statements, choose the correct answer from the options given below:

(C) Statement I is true but Statement II is false

(A) Statement I is false but Statement II is true

(B) Both Statement I and Statement II are false

(D) Both Statement I and Statement II are true

JEE Main · 2025 · 04 Apr 2025 · Shift 1 · General Organic Chemistry

Given below are two statements.

Statement I : The dipole moment of

CH 4 - CH 3 = CH 2 - CH 1 = O

is greater than (see structure)

Statement II:

C_{1} - C_{2}

bond length of (see structure) is greater than

C_{1} - C_{2}

bond length of (see structure)

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

(A)Statement I is false but Statement II is true
(B)Both Statement I and Statement II are false
(C)Statement I is true but Statement II is false✓ Correct
(D)Both Statement I and Statement II are true

Answer: (C)

Solution

Butanal carries only the polar carbonyl group, whereas but-2-enal has its

C = C

conjugated with the

C = O

; this conjugation delocalizes charge over a longer path and gives but-2-enal the larger dipole moment, so the first statement is correct. The same conjugation gives the

C_{1} - C_{2}

bond of but-2-enal partial double-bond character, making it shorter, not longer, than the ordinary

C_{1} - C_{2}

single bond of butanal, so the second statement is wrong. Only the first statement is true.

JEE Main · 2025 · 04 Apr 2025 · Shift 1 · Single correct option

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JEE Main · 2025 · 04 Apr 2025 · Shift 1 · General Organic Chemistry

Solution

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