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Hydrocarbons

JEE Main 2025 (Online) 2nd April Morning ShiftMCQMedium📈 Topic in 24% papers+4−1
Ques. 1JEE 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

Answer

(3) Butan-2-one

Solution

The only optically active C4H9Br is 2-bromobutane: [A] = CH3- *CHBr-CH2-CH3

[A] alc. KOH, [B] = CH3-CH=CH-CH3 (but-2-ene, Saytzeff product)

[B] Br2 [C] = CH3-CHBr-CHBr-CH3 (2,3-dibromobutane)

[C] alc. NaNH2 [D] = CH3-C C-CH3 (but-2-yne, gas) by double dehydrohalogenation

[D] [333 K] H2O, Hg2+/H+ CH3-C(OH)=CH-CH3 (enol) CH3-CO-CH2-CH3

[E] = butan-2-one

Answer: (3)

Keep practising — Hydrocarbons

Ques. 2JEE 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. 3JEE 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
Ques. 4JEE Main 2025, 29 January (Evening Shift)

Isomeric hydrocarbons negative Baeyer's test (Molecular formula C9H12) The total number of isomers from above with four different non-aliphatic substitution sites is -

Ques. 5JEE Main 2025, 28 January (Morning Shift)

A molecule (P) on treatment with acid undergoes rearrangement and gives (Q). (Q) on ozonolysis followed by reflux under alkaline condition gives (R). The structure of (R) is given below. [figure] The structure of (P) is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 6JEE Main 2025, 28 January (Evening Shift)

Identify product [A], [B] and [C] in the following reaction sequence. CH3-C CH [H2]Pd/C [A] [(ii) Zn, H2O](i) O3 [B] + [C]

  1. [A]: CH3-CH=CH2, [B]: CH3CHO, [C]: CH3CH2OH
  2. [A]: CH3-CH=CH2, [B]: CH3CHO, [C]: HCHO
  3. [A]: CH3CH2CH3, [B]: CH3CHO, [C]: HCHO
  4. [A]: CH2=CH2, [B]: H3C- O \|C-CH3, [C]: HCHO
Ques. 7JEE Main 2025, 24 January (Morning Shift)

The product (A) formed in the following reaction sequence is [figure]

  1. CH3-CH2- OH |CH-CH2-NH2
  2. CH3-CH2- NH2 |CH-CH2-NH2
  3. CH3- CH3 | OH |C-CH2-NH2
  4. CH3- CH3 | NH2 |C-CH2-OH
Ques. 8JEE Main 2025, 24 January (Morning Shift)

Following are the four molecules "P", "Q", "R" and "S". Which one among the four molecules will react with H-Br(aq) at the fastest rate? [figure]

  1. Q
  2. S
  3. P
  4. R
Ques. 9JEE Main 2025, 24 January (Evening Shift)

Identify correct statement/s : Choose the correct answer from the options given below :

  1. A, C and D only
  2. A, B and E only
  3. A and C only
  4. A only
Ques. 10JEE Main 2025, 23 January (Morning Shift)

Propane molecule on chlorination under photochemical condition gives two di-chloro products, “x” and “y”. Amongst “x” and “y”, “x” is an optically active molecule. How many tri-chloro products (consider only structural isomers) will be obtained from “x” when it is further treated with chlorine under the photochemical condition?

  1. 4
  2. 2
  3. 3
  4. 5
Ques. 11JEE Main 2025, 23 January (Evening Shift)

Match List - I with List - II Choose the correct answer from the options given below :

  1. A-III, B-IV, C-I, D-II
  2. A-I, B-IV, C-III, D-II
  3. A-III, B-II, C-I, D-IV
  4. A-II, B-II, C-I, D-IV

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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