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Hydrocarbons

JEE Main 2026 (Online) 23rd January Evening ShiftMCQHard📈 Topic in 27% papers+4−1
Ques. 1JEE Main 2026, 23 January (Evening Shift)

[figure] Identify (P)

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(4) [figure]

Solution

Step 1: Zn, removes the two vicinal Br atoms (dehalogenation) a C=C bond is formed between the two carbons that carried Br.

Step 2: H+ of HBr adds to the double bond a 2° carbocation is formed next to either the ethyl-bearing or the methyl-bearing ring carbon.

A 1,2-hydride shift converts this 2° carbocation into a more stable 3° carbocation.

The 3° carbocation on the methyl-bearing carbon has 7 α-H atoms (3 of CH3 + 2 + 2 of the ring CH2 groups), while the one on the ethyl-bearing carbon has only 6 α-H atoms (2 of CH2CH3 + 2 + 2),

the carbocation on the carbon carrying CH3 is more stabilised by hyperconjugation.

Br- attacks this carbocation:

[figure]

(P) is 1-bromo-3-ethyl-1-methylcyclopentane, i.e. option (4).

Answer: (4)

Keep practising — Hydrocarbons

Ques. 2JEE Main 2026, 22 January (Morning Shift)

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

  1. Statement I is incorrect but Statement II is correct
  2. Both Statement I and Statement II are correct
  3. Both Statement I and Statement II are incorrect
  4. Statement I is correct but Statement II is incorrect
Ques. 3JEE Main 2026, 22 January (Morning Shift)

The cycloalkene (X) on bromination consumes one mole of bromine per mole of (X) and gives the product (Y) in which C : Br ratio is 3:1. The percentage of bromine in the product (Y) is %. (Nearest integer) (Given : molar mass in g mol-1 H : 1, C : 12, O : 16, Br : 80)

Ques. 4JEE Main 2026, 22 January (Evening Shift)

Consider the following reaction : [figure] The product Y formed is :

  1. 2-methylhex-3-yne
  2. 5-methylhex-2-yne
  3. Isopropylbut-1-yne
  4. 2-methylhex-2-yne
Ques. 5JEE Main 2026, 22 January (Evening Shift)

The dibromo compound [P] (molecular formula: C9H10Br2) when heated with excess sodamide followed by treatment with dilute HCl gives [Q]. On warming [Q] with mercuric sulphate and dilute sulphuric acid yields [R] which gives positive Iodoform test but negative Tollens' test. The compound [P] is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 6JEE Main 2026, 21 January (Morning Shift)

Identify A in the following reaction. [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 7JEE Main 2025, 8 April (Evening Shift)

[figure] 'P' is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 8JEE Main 2025, 8 April (Evening Shift)

Choose the correct set of reagents for the following conversion. [figure]

  1. Cl2/ anhy. AlCl3; Br2/Fe; alc. KOH
  2. Cl2/Fe; Br2/ anhy. AlCl3; aq. KOH
  3. Br2/Fe; Cl2, ; alc. KOH
  4. Br2/ anhy. AlCl3; Cl2, ; aq. KOH
Ques. 9JEE Main 2025, 7 April (Morning Shift)

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. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Both Statement I and Statement II are true
Ques. 10JEE Main 2025, 7 April (Evening Shift)

Identify the structure of the final product (D) in the following sequence of the reactions : [figure] Total number of sp2 hybridised carbon atoms in product D is .

Ques. 11JEE Main 2025, 4 April (Morning Shift)

Predict the major product of the following reaction sequence: [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

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