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Organic Chemistry – Some Basic Principles and Techniques · Question 25

JEE Main 2025 (Online) 4th April Morning ShiftMCQMedium📈 Topic in 16% papers+4−1
1

Given below are two statements. In the light of the above statements, choose the correct answer from the options given below:

  1. Both Statement I and Statement II are true
  2. Statement I is true but Statement II is false
  3. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are false

Answer

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

Solution

But-2-enal is a conjugated system and shows resonance (−R effect of C=O):

CH3-CH=CH-CH=O CH3- CH-CH=CH- O

Statement I: in but-2-enal the charges are separated over a longer distance (C-3 to O) in the polar resonance form, so = q d is larger than in butanal, where only the C=O group is polar. True.

Statement II: due to resonance the C1-C2 bond of but-2-enal has partial double bond character and joins two sp2 carbons, while in butanal it is a pure single bond between sp2 C-1 and sp3 C-2. So the C1-C2 bond in but-2-enal is shorter. False.

Answer: (2)

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2

The IUPAC name of the following compound is: HC C-CH2- OH |CH-CH2-CH=CH2

  1. 4-Hydroxyhept-6-en-1-yne
  2. Hept-1-en-6-yn-4-ol
  3. Hept-6-en-1-yn-4-ol
  4. 4-Hydroxyhept-1-en-6-yne
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3

In which pairs, the first ion is more stable than the second?

  1. (A) & (B) only
  2. (B) & (D) only
  3. (A) & (C) only
  4. (B) & (C) only
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4

The correct order of basicity for the following molecules is : [figure]

  1. R > P > Q
  2. P > Q > R
  3. R > Q > P
  4. Q > P > R
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5

The least acidic compound, among the following is: [figure]

  1. B
  2. D
  3. A
  4. C
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6

What is the correct IUPAC name of [figure] ?

  1. 3-Bromo-2-hydroxy-5-nitrobenzoic acid
  2. 2-Hydroxy-3-bromo-5-nitrobenzoic acid
  3. 3-Bromo-4-hydroxy-1-nitrobenzoic acid
  4. 5-Nitro-3-bromo-2-hydroxybenzoic acid
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7

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

  1. Statement I is false but Statement II is true
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are false
  4. Both Statement I and Statement II are true
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8

Consider the following compound (X) [figure] The most stable and least stable carbon radicals, respectively, produced by homolytic cleavage of corresponding C-H bond are :

  1. III, II
  2. II, IV
  3. I, IV
  4. II, I
JEE Main 2025 (Online) 2nd April Morning Shift
9

Designate whether each of the following compounds is aromatic or not aromatic. [figure]

  1. a, c, d, e, h aromatic and b, f, g not aromatic
  2. b, e, f, g aromatic and a, c, d, h not aromatic
  3. a, b, c, d aromatic and e, f, g, h not aromatic
  4. e, g aromatic and a, b, c, d, f, h not aromatic
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10

In 3,3-dimethylhex-1-en-4-yne, there are sp3, sp2 and sp hybridised carbon atoms respectively.

  1. 4, 2, 2
  2. 2, 4, 2
  3. 3, 3, 2
  4. 2, 2, 4
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11

Match List - I with List - II. Choose the correct answer from the options given below :

  1. (A)-(II), (B)-(III), (C)-(IV), (D)-(I)
  2. (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
  3. (A)-(III), (B)-(IV), (C)-(I), (D)-(II)
  4. (A)-(III), (B)-(II), (C)-(I), (D)-(IV)
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