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Hydrocarbons · Question 31

JEE Main 2025 (Online) 28th January Evening ShiftMCQEasy📈 Topic in 26% papers+4−1
1

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)

JEE Main 2025 (Online) 28th January Evening Shift

Keep practising — Hydrocarbons

2

n-Butane on monochlorination under photochemical condition gives an optically active compound "P". "P" on further chlorination gives dichloro compounds. The number of dichloro compounds obtained (ignore stereoisomers) is :

  1. 3
  2. 4
  3. 5
  4. 6
JEE Main 2026 (Online) 8th April Evening Shift
3

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 6th April Morning Shift
4

An optically active alkyl bromide C4H9Br, reacts with ethanolic KOH to form major compound [A] which reacts with bromine to give compound [B]. Compound [B] reacts with ethanolic KOH and sodamide to give compound [C]. One molecule of water adds to compound [C] on warming with mercuric sulphate and dilute sulphuric acid at 333 K to form compound [D]. The functional group in compound D will be confirmed by :

  1. Haloform test
  2. Lucas test
  3. Silver mirror test
  4. Benedict test
JEE Main 2026 (Online) 6th April Evening Shift
5

An alkane (Y) requires 8 moles of oxygen for complete combustion and on chlorination with Cl2/h , (Y) gives only one monochlorinated product (Z). The total number of primary carbon atoms in (Y) is .

JEE Main 2026 (Online) 6th April Evening Shift
6

For the following Friedel Craft's alkylation reaction, which of the statements are correct? [figure] Choose the correct answer from the options given below :

  1. A and D only
  2. B and C only
  3. A and C only
  4. B and D only
JEE Main 2026 (Online) 5th April Morning Shift
7

An alkene (X) on ozonolysis followed by reduction gives following products. H- O \|C-H (2 moles), H- O \|C- O \|C- O \|C-H, CH3- O \|C- O \|C- O \|C-CH3 The alkene (X) is :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2026 (Online) 4th April Morning Shift
8

[figure] Compound (X) is subjected to the sequence of reactions as shown above. Molar mass of the major product (Y) formed is g mol-1. (Given molar mass in g mol-1 C : 12, H : 1, O : 16 )

  1. 90
  2. 118
  3. 160
  4. 125
JEE Main 2026 (Online) 4th April Evening Shift
9

One mole of an alkane (x) requires 8 mole oxygen for complete combustion. Sum of number of carbon and hydrogen atoms in the alkane (x) is .

JEE Main 2026 (Online) 2nd April Morning Shift
10

The compound (X) on (i) on heating in the presence of anhydrous AlCl3 and HCl gas gives 2,4-dimethyl pentane (ii) aromatization gives toluene and (iii) cyclisation gives methyl cyclohexane The correct name of compound (X) is:

  1. Hept-2-ene
  2. Hept-1,3,5-triene
  3. Heptane
  4. Hept-2,4,6-triene
JEE Main 2026 (Online) 2nd April Evening Shift
11

Given below are two statements for the following reaction sequence. [figure] 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. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are false
JEE Main 2026 (Online) 28th January Morning Shift

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