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Aldehydes, Ketones and Carboxylic Acids

JEE Main 2026 (Online) 23rd January Morning ShiftMCQMedium📈 Topic in 27% papers+4−1
Ques. 1JEE Main 2026, 23 January (Morning Shift)

'x' is the product which is obtained from propanenitrile and stannous chloride in the presence of hydrochloric acid followed by hydrolysis. 'y' is the product which is obtained from the but-2-ene by the ozonolysis followed by hydrolysis. From the following, which product is not obtained when one mole of 'x' and one mole of 'y' react with each other in the presence of alkali followed by heating?

  1. 2-Methylpent-2-enal
  2. 2-Methylbut-2-enal
  3. 3-Methylbut-2-enal
  4. Pent-2-enal

Answer

(3) 3-Methylbut-2-enal

Solution

Stephen reaction: CH3CH2C N [H3O+]SnCl2/HCl CH3CH2CHO x = propanal

Ozonolysis: CH3CH=CHCH3 [Zn/H2O]O3 2 CH3CHO y = ethanal

Both have α-hydrogens, so dilute alkali and heat give four aldol condensation products:

Ethanal + ethanal CH3CH=CHCHO (but-2-enal)

Propanal + propanal CH3CH2CH=C(CH3)CHO (2-methylpent-2-enal)

Enolate of propanal + ethanal CH3CH=C(CH3)CHO (2-methylbut-2-enal)

Enolate of ethanal + propanal CH3CH2CH=CHCHO (pent-2-enal)

3-Methylbut-2-enal, (CH3)2C=CHCHO, would need acetone as the carbonyl partner, so it is not formed.

Answer: (3)

Keep practising — Aldehydes, Ketones and Carboxylic Acids

Ques. 2JEE Main 2026, 23 January (Morning Shift)

[figure] The correct sequence of reagents for the above conversion of X to Y is :

  1. (i) NaOH(aq), (ii) Jones reagent, (iii) H3O+
  2. (i) NaOEt, (ii) B2H6/H2O2, (iii) Jones reagent
  3. (i) Jones reagent, (ii) NaOEt, (iii) Hot KMnO4/KOH
  4. (i) B2H6/H2O2, (ii) NaOEt, (iii) Jones reagent
Ques. 3JEE Main 2026, 23 January (Evening Shift)

Which of the following statements are TRUE about Haloform reaction? Choose the correct answer from the options given below :

  1. A, B & C Only
  2. A, C & E Only
  3. B, D & E Only
  4. A & C Only
Ques. 4JEE Main 2026, 23 January (Evening Shift)

Iodoform test can differentiate between Choose the correct answer from the options given below :

  1. A, B & E Only
  2. A & D Only
  3. A & E Only
  4. B, C & E Only
Ques. 5JEE Main 2026, 23 January (Evening Shift)

Consider the following reaction of benzene. [figure] In compound (Q), the percentage of oxygen is %. (Nearest integer)

Ques. 6JEE Main 2026, 22 January (Morning Shift)

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

  1. A-IV, B-III, C-II, D-I
  2. A-III, B-I, C-IV, D-II
  3. A-II, B-I, C-IV, D-III
  4. A-III, B-IV, C-I, D-II
Ques. 7JEE Main 2026, 22 January (Evening Shift)

The compound A, C8H8O2 reacts with acetophenone to form a single product via cross-Aldol condensation. The compound A on reaction with conc. NaOH forms a substituted benzyl alcohol as one of the two products. The compound A is :

  1. 2-hydroxy acetophenone
  2. 4-hydroxy benzaldehyde
  3. 4-methyl benzoic acid
  4. 4-methoxy benzaldehyde
Ques. 8JEE Main 2026, 21 January (Morning Shift)

An organic compound "P" of molecular formula C6H12O3 gives positive iodoform test but negative Tollens' test. When "P" is treated with dilute acid, it produces "Q". "Q" gives positive Tollens' test and also iodoform test. The structure of "P" is :

  1. H- O \|C-CH2-CH2- OCH3 |CH-OCH3
  2. CH3- O \|C- OCH3 |CH- OCH3 |CH2
  3. CH3- O \|C-CH2- OCH3 |CH-OCH3
  4. CH3- O \|C- OCH3 | OCH3 |C-CH3
Ques. 9JEE Main 2026, 21 January (Evening Shift)

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

  1. A-II, B-III, C-IV, D-I
  2. A-IV, B-III, C-I, D-II
  3. A-IV, B-I, C-II, D-III
  4. A-II, B-IV, C-I, D-III
Ques. 10JEE Main 2025, 8 April (Evening Shift)

A [(ii) H3O+](i) NaOH B [(ii) H2SO4, ](i) EtOH C 'A' shows positive Lassaigne's test for N and its molar mass is 121. 'B' gives effervescence with aq NaHCO3. 'C' gives fruity smell. Identify A, B and C from the following.

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 11JEE Main 2025, 8 April (Evening Shift)

When [figure] undergoes intramolecular aldol condensation, the major product formed is :

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

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