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Organic Chemistry – Some Basic Principles and Techniques · Question 27

JEE Main 2025 (Online) 4th April Evening ShiftMCQMedium📈 Topic in 10% papers+4−1
1

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

Answer

(1) (A) & (B) only

Solution

(A) First: the lone pair of –OMe oxygen delocalises onto C (+R), giving a structure in which every atom has an octet ( O=C). Second: only +I and hyperconjugation of –Me.

First is more stable. ✓

(B) First: the carbanion is conjugated with the benzene ring bearing an ortho –NO2 group; the negative charge is delocalised onto the ring and the nitro oxygens (–R, –I) highly stabilised.

Second: the carbocation is attached to a ring bearing an ortho –NO2 group, whose –R and –I effects destabilise the positive charge.

First is more stable. ✓

(C) First: a primary carbocation (only +I / hyperconjugation). Second: the CH2 is attached to a C=C (allylic carbocation), stabilised by resonance.

Second is more stable. ✗

(D) First: tert-butyl carbocation (+I and 9 hyperconjugating H). Second: –OMe on C gives +R stabilisation, which outweighs hyperconjugation.

Second is more stable. ✗

(A) & (B) only.

Answer: (1)

JEE Main 2025 (Online) 4th April Evening Shift

Keep practising — Organic Chemistry – Some Basic Principles and Techniques

2

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
JEE Main 2025 (Online) 4th April Evening Shift
3

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

  1. B
  2. D
  3. A
  4. C
JEE Main 2025 (Online) 3rd April Morning Shift
4

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
JEE Main 2025 (Online) 3rd April Evening Shift
5

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
JEE Main 2025 (Online) 3rd April Evening Shift
6

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
7

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
JEE Main 2025 (Online) 2nd April Morning Shift
8

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
JEE Main 2025 (Online) 2nd April Evening Shift
9

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)
JEE Main 2025 (Online) 29th January Morning Shift
10

Total number of nucleophiles from the following is : NH3, PhSH, (H3C)2S, H2C=CH2, OH, H3O , (CH3)2 CO, [figure]

  1. 4
  2. 6
  3. 5
  4. 7
JEE Main 2025 (Online) 29th January Morning Shift
11

The correct order of stability of following carbocations is : [figure]

  1. A > B > C > D
  2. C > B > A > D
  3. B > C > A > D
  4. C > A > B > D
JEE Main 2025 (Online) 28th January Morning Shift

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