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Hydrocarbons

JEE Main 2026 (Online) 23rd January Morning ShiftMCQMedium📈 Topic in 29% papers+4−1
Ques. 1JEE Main 2026, 23 January (Morning Shift)

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)

Keep practising — Hydrocarbons

Ques. 2JEE Main 2026, 23 January (Evening Shift)

[figure] Identify (P)

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 3JEE 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. 4JEE 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. 5JEE 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. 6JEE 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. 7JEE Main 2026, 21 January (Morning Shift)

Identify A in the following reaction. [figure]

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

[figure] 'P' is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 9JEE 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. 10JEE 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. 11JEE 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 .

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All JEE Main Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolutionsElectrochemistryChemical Kinetics
Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular Structurep-Block Elements (Group 13 & 14)p-Block Elements (Group 15–18)d- and f-Block ElementsCoordination Compounds
Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPrinciples Related to Practical Chemistry