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Hydrocarbons

JEE Main 2025 (Online) 8th April Evening ShiftMCQMedium📈 Topic in 16% papers+4−1
Ques. 1JEE 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

Answer

(3) Br2/Fe; Cl2, ; alc. KOH

Solution

Step 1 – Br2/Fe: electrophilic substitution on the ring; –C2H5 is o/p-directing, the para product is major.

Step 2 – Cl2, : free-radical chlorination at the benzylic carbon (most stable benzylic radical).

Step 3 – alc. KOH: dehydrochlorination (elimination) forms the C=C.

[figure]

Other options fail: (1) and (2) put Cl on the ring with a Lewis-acid catalyst instead of on the side chain; (2) and (4) use aq. KOH, which substitutes Cl by OH (alcohol) instead of eliminating HCl.

Answer: (3)

Keep practising — Hydrocarbons

Ques. 2JEE 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. 3JEE 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. 4JEE 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. 5JEE 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. 6JEE 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. 7JEE 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. 8JEE 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. 9JEE 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. 10JEE 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. 11JEE 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]

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Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPrinciples Related to Practical Chemistry