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Hydrocarbons

JEE Main 2026 (Online) 21st January Morning ShiftMCQMedium📈 Topic in 27% papers+4−1
Ques. 1JEE Main 2026, 21 January (Morning Shift)

Identify A in the following reaction. [figure]

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

Answer

(1) [figure]

Solution

A 2H2/Pt decalin, so A has the decalin skeleton with two C=C bonds.

Hot KMnO4 cleaves each C=C, and every =CH– carbon is oxidised to –COOH; the products are cyclohexane-1,2-dicarboxylic acid and oxalic acid (HOOC-COOH).

Since the cyclohexane ring of the product is not broken, one ring is saturated, so both C=C must be in the other ring as a diene C1=C2-C3=C4, with C1 and C4 bonded to the two ring-fusion carbons.

Cleavage of C1=C2 and C3=C4 turns C1 and C4 into two –COOH on adjacent ring carbons, while C2-C3 becomes HOOC-COOH. This is structure (1).

(2): one double bond is at the ring fusion, so its cleavage opens both rings (no cyclohexane-1,2-dicarboxylic acid).

(3), (4): there is one double bond in each ring, so both rings are cleaved and no oxalic acid is formed.

Answer: (1)

Keep practising — Hydrocarbons

Ques. 2JEE Main 2025, 8 April (Evening Shift)

[figure] 'P' is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 3JEE 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. 4JEE 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. 5JEE 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. 6JEE Main 2025, 4 April (Morning Shift)

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

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

Consider the following molecule(X). [figure] The major product formed when the given molecule (X) is treated with HBr (1 eq) is :

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

Which compound would give 3-methyl-6-oxoheptanal upon ozonolysis?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 9JEE Main 2025, 2 April (Morning Shift)

An optically active alkyl halide C4H9Br [A] reacts with hot KOH dissolved in ethanol and forms alkene [B] as major product which reacts with bromine to give dibromide [C]. The compound [C] is converted into a gas [D] upon reacting with alcoholic NaNH2. During hydration 18 gram of water is added to 1 mole of gas [D] on warming with mercuric sulphate and dilute acid at 333 K to form compound [E]. The IUPAC name of compound [E] is :

  1. Butan-2-ol
  2. But-2-yne
  3. Butan-2-one
  4. Butan-1-al
Ques. 10JEE Main 2025, 2 April (Evening 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. Statement I is correct but Statement II is incorrect
  4. Both Statement I and Statement II are incorrect
Ques. 11JEE Main 2025, 29 January (Evening 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 true but Statement II is false
  2. Both Statement I and Statement II are true
  3. Both Statement I and Statement II are false
  4. Statement I is false but Statement II is true

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All JEE Main Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolid StateSolutionsElectrochemistryChemical Kinetics
Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular Structures-Block Elementsp-Block Elements (Group 13 & 14)Environmental ChemistryGeneral Principles of Isolation of Elementsp-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