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Hydrocarbons · Question 14

JEE Main 2026 (Online) 23rd January Morning ShiftMCQMedium📈 Topic in 26% papers+4−1
1

But-2-yne and hydrogen (one mole each) are separately treated with (i) Pd/C and (ii) Na/ liq. NH3 to give the products X and Y respectively. [figure] Identify the incorrect statements. Choose the correct answer from the options given below :

  1. B and D Only
  2. A and C Only
  3. A and B Only
  4. B and C Only

Answer

(1) B and D Only

Solution

With one mole of H2 on Pd/C, both H atoms add from the catalyst surface on the same side (syn addition) X = cis-but-2-ene

Reduction with Na/liq. NH3 gives anti addition Y = trans-but-2-ene

[figure]

A. X and Y are geometrical isomers, i.e. stereoisomers correct

B. In cis-but-2-ene the two C-CH3 bond moments do not cancel, so its dipole moment is not zero incorrect

C. cis-But-2-ene is polar, so it has stronger dipole–dipole attractions and a higher boiling point (277 K) than trans-but-2-ene (274 K) correct

D. Ozonolysis of both gives the same product, two molecules of ethanal (CH3CHO) incorrect

Incorrect statements: B and D

Answer: (1)

JEE Main 2026 (Online) 23rd January Morning Shift

Keep practising — Hydrocarbons

2

[figure] Identify (P)

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 23rd January Evening Shift
3

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
JEE Main 2026 (Online) 22nd January Morning Shift
4

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)

JEE Main 2026 (Online) 22nd January Morning Shift
5

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
JEE Main 2026 (Online) 22nd January Evening Shift
6

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]
JEE Main 2026 (Online) 22nd January Evening Shift
7

Identify A in the following reaction. [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 21st January Morning Shift
8

[figure] 'P' is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 8th April Evening Shift
9

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
JEE Main 2025 (Online) 8th April Evening Shift
10

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
JEE Main 2025 (Online) 7th April Morning Shift
11

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 .

JEE Main 2025 (Online) 7th April Evening Shift

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