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Hydrocarbons

JEE Main 2025 (Online) 28th January Evening ShiftMCQEasy📈 Topic in 29% papers+4−1
Ques. 1JEE 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

Answer

(2) [A]: CH3-CH=CH2, [B]: CH3CHO, [C]: HCHO

Solution

Step 1: as per NCERT, an alkyne with a calculated amount of H2 over palladised charcoal (Pd/C, partially deactivated) is reduced only up to the alkene stage:

CH3-C CH + H2 Pd/C CH3-CH=CH2 = [A] (propene)

Step 2: reductive ozonolysis cleaves the C=C bond and puts a C=O on each carbon:

CH3-CH=CH2 [(ii) Zn, H2O](i) O3 CH3CHO + HCHO

[B] = CH3CHO (ethanal), [C] = HCHO (methanal).

Answer: (2)

Keep practising — Hydrocarbons

Ques. 2JEE 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. 3JEE 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. 4JEE 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. 5JEE 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. 6JEE 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
Ques. 7JEE Main 2025, 23 January (Evening Shift)

A compound ' X ' absorbs 2 moles of hydrogen and ' X ' upon oxidation with KMnO4 | H+ gives [figure] The total number of bonds present in the compound ' X ' is .

Ques. 8JEE Main 2025, 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. Both Statement I and Statement II are incorrect
  2. Statement I is incorrect but Statement II is correct
  3. Both Statement I and Statement II are correct
  4. Statement I is correct but Statement II is incorrect
Ques. 9JEE Main 2025, 22 January (Evening Shift)

When sec-butylcyclohexane reacts with bromine in the presence of sunlight, the major product is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 10JEE Main 2025, 22 January (Evening Shift)

The compound with molecular formula C6H6, which gives only one monobromo derivative and takes up four moles of hydrogen per mole for complete hydrogenation has electrons.

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