Aldehydes, Ketones & Acids

23 JEE Main questions · Chemistry

ChemistryJEE Main 21 Jan 2026, Shift 1·Q11·MCQ·Moderate
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Acetal hydrolysis and iodoform test
An organic compound “P” of molecular formula $\ce{C6H12O3}$ gives positive Iodoform test but negative Tollen's test. When “P” is treated with dilute acid, it produces “Q”. “Q” gives positive Tollen's test and also iodoform test. The structure of “P” is :
1. (1)
2. (2)
3. (3)
4. (4)

ChemistryJEE Main 21 Jan 2026, Shift 2·Q7·MCQ·Easy

Named reactions for aldehyde preparation

Match List-I with List-II.

	List-I (Reagents)		List-II (Reaction Name (Involving aldehydes))
A.	$\ce{H2}$ , Pd- $\ce{BaSO4}$	I.	Etard Reaction
B.	$\ce{SnCl2}$ , HCl	II.	Rosenmund Reduction
C.	$\ce{CrO2Cl2}$ , $\ce{CS2}$	III.	Gatterman – Koch Reaction
D.	CO, HCl, Anhyd. $\ce{AlCl3}$	IV.	Stephen Reaction

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

ChemistryJEE Main 22 Jan 2026, Shift 1·Q13·MCQ·Easy

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Carbonyl tests and reductions

Match the LIST-I with LIST-II

List-I		List-II
Reagents		Name of Reaction involving carbonyl compound
A.	$\ce{NH2-NH2}$ , KOH	I.	Tollen's Test
B.	$\ce{Ag(NH3)2OH}$	II.	Clemmensen Reduction
C.	Aq. $\ce{CuSO4}$ , Sodium Potassium tartrate, KOH	III.	Wolff-Kishner Reduction
D.	Zn – Hg, HCl	IV.	Fehling's Test

Choose the correct answer from the options given below

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

We corrected a printing error in the original paper

Source printed “Sodium Potassium tartarate”.

ChemistryJEE Main 22 Jan 2026, Shift 2·Q18·MCQ·Easy–moderate
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Cross aldol and cannizzaro reaction
The compound A, $\ce{C8H8O2}$ 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. The compound A is :
1. (1)2-hydroxy acetophenone
2. (2)4-methoxy benzaldehyde
3. (3)4-hydroxy benzylaldehyde
4. (4)4-methyl benzoic acid
We corrected a printing error in the original paper
Source printed “forms a substituted benzyl alcohol as” (the question asked for A was missing; no option is a benzyl alcohol) and, in option (2), “4-methyoxy benzaldehyde”.
ChemistryJEE Main 23 Jan 2026, Shift 1·Q6·MCQ·Moderate
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Cross aldol condensation
‘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. (1)2-Methylbut-2-enal
2. (2)Pent-2-enal
3. (3)2-Methylpent-2-enal
4. (4)3-Methylbut-2-enal
ChemistryJEE Main 23 Jan 2026, Shift 2·Q8·MCQ·Easy–moderate
Open
Iodoform test
Iodoform test can differentiate between
- (A)Methanol and Ethanol
- (B) $\ce{CH3COOH}$ and $\ce{CH3CH2COOH}$
- (C)Cyclohexene and cyclohexanone
- (D)Diethyl ether and Pentan-3-one
- (E)Anisole and acetone
Choose the correct answer from the options given below:
1. (1)A & E only
2. (2)A & D only
3. (3)A, B & E only
4. (4)B, C & E only
ChemistryJEE Main 23 Jan 2026, Shift 2·Q12·MCQ·Easy–moderate
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Haloform reaction
Which of the following statements are TRUE about Haloform reaction?
- (A)Sodium hypochlorite reacts with KI to give KOI.
- (B)KOI is a reducing agent.
- (C) $\alpha$ , $\beta$ -unsaturated methylketone will give iodoform reaction.
- (D)Isopropyl alcohol will not give iodoform test.
- (E)Methanoic acid will give positive iodoform test.
Choose the correct answer from the options given below:
1. (1)A, C & E only
2. (2)A, B & C only
3. (3)A & C only
4. (4)B, D & E only
ChemistryJEE Main 23 Jan 2026, Shift 2·Q25·Numerical·Moderate
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Intramolecular aldol condensation
In compound (Q), the percentage of oxygen is %. (Nearest integer)
We corrected a printing error in the original paper
Answer supplied; the source prints no answer key for this question (its worked solution gives 10.19%; Q = 3-phenylcyclopent-2-en-1-one, $\ce{C11H10O}$ , 16/158 = 10.1%).
ChemistryJEE Main 24 Jan 2026, Shift 1·Q14·MCQ·Easy–moderate
Open
Tollens test on cyclic hemiacetal
A student is given one compound among the following compounds that gives positive test with Tollen's reagent.
The compound is :
1. (1)D
2. (2)A
3. (3)B
4. (4)C
ChemistryJEE Main 24 Jan 2026, Shift 2·Q2·MCQ·Easy–moderate
Open
Distinguishing aldehydes from ketones
The unsaturated ether on acidic hydrolysis produces carbonyl compounds as shown below:-
$\ce{CH3-CH=CH-O-CH=CH2}$
$\downarrow$ $\ce{H3O^{(+)}}$
$\ce{CH3-CH2-CH=O}$ and $\ce{O=CH-CH3}$
Based on this, predict the solution / reagent that will help to distinguish “P” and “Q” obtained in the following reaction.
1. (1)Lucas reagent
2. (2)2,4-DNP reagent
3. (3)Saturated $\ce{NaHSO3}$ solution
4. (4)Fehling solution
ChemistryJEE Main 24 Jan 2026, Shift 2·Q14·MCQ·Easy–moderate
Open
Cross aldol and carbonyl reactivity
Given below are two statements :
Statement I : Cross aldol condensation between two different aldehydes will always produce four different products.
Statement II : When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH, it forms a condensation product with acetophenone only.
In the light of the above statements, choose the correct answer from the options given below :
1. (1)Both Statement I and Statement II are false
2. (2)Statement I is false but Statement II is true
3. (3)Both Statement I and Statement II are true
4. (4)Statement I is true but Statement II is false
ChemistryJEE Main 24 Jan 2026, Shift 2·Q25·Numerical·Easy–moderate
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Grignard carboxylation
Grignard reagent RMgBr(P) reacts with water and forms a gas (Q). One gram of Q occupies 1.4 dm $^3$ at STP. (P) on reaction with dry ice in dry ether followed by $\ce{H3O+}$ forms a compound (Z). 0.1 mole of (Z) will weigh g. (Nearest integer)
ChemistryJEE Main 28 Jan 2026, Shift 1·Q9·MCQ·Moderate
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Tests for carbonyl compounds
Given below are the four isomeric compounds (P, Q, R, S)
Identify correct statements from below.
- (A)Q, R and S will give precipitate with 2, 4 - DNP.
- (B)P and Q will give positive Baeyer's test.
- (C)Q and R will give sooty flame.
- (D)R and S will give yellow precipitate with $\ce{I2}$ /NaOH.
- (E)Q alone will deposit silver with Tollen's reagent
Choose the correct option.
1. (1)A, C and E only
2. (2)A and E only
3. (3)C and E only
4. (4)A, B, D and E only
We corrected a printing error in the original paper
Source printed “Bayer's test”.
ChemistryJEE Main 28 Jan 2026, Shift 2·Q15·MCQ·Moderate
Open
Acidic strength of carboxylic acids
The correct order of acidic strength of the major products formed in the given reactions, is :
- (A) $\mathrm{PhNH_2}\xrightarrow[\substack{\text{(2) }\ce{CuCN}\\ \text{(3) }\ce{H3O+}/\Delta}]{\text{(1) }\ce{NaNO2 + HCl}\,(<5^\circ\mathrm{C})}[\mathrm{A}]$
- (B) $\ce{CH3CH2CHO}\xrightarrow[\Delta]{\ce{[Ag(NH3)2]+}\text{, }\ce{OH-}}[\mathrm{B}]$
- (C) $\ce{CH4 + O2}\xrightarrow[\text{(ii) }\ce{Na2Cr2O7}/\ce{H+}]{\text{(i) }\ce{Mo2O3}}[\mathrm{C}]$
- (D) $\ce{PhCH2MgBr + CO2}\xrightarrow[\ce{H3O+}]{\text{Dry ether}}[\mathrm{D}]$
Choose the correct answer from the options given below :
1. (1)C $>$ B $>$ A $>$ D
2. (2)A $>$ D $>$ C $>$ B
3. (3)A $>$ D $>$ B $>$ C
4. (4)C $>$ A $>$ D $>$ B
ChemistryJEE Main 2 Apr 2026, Shift 2·Q16·MCQ·Moderate
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Intramolecular cannizzaro of glyoxal
An organic compound “x” where molar ratio of C, O and H are equal, on treatment with 50% KOH under reflux followed by acidification produced “y”. The most likely structure of “y” is:
[Molar mass of ‘x' is 58 g mol $^{-1}$ ]
1. (1)
2. (2) $\ce{CH3-CH=CH-CH=O}$
3. (3)
4. (4)
ChemistryJEE Main 2 Apr 2026, Shift 2·Q17·MCQ·Moderate
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Enol ether hydrolysis carbonyl tests
A molecule (X) with following structure under mild acidic condition is hydrolysed to produce (Y) and (Z). Identify the correct statements about (Y) and (Z).
- (A)Both (Y) and (Z) have same molar mass
- (B)(Y) and (Z) can be distinguished from each other by $\ce{NaHCO3}$
- (C)(Y) and (Z) react with HCN with same rates
- (D)(Y) and (Z) undergo addition reaction with 2, 4-DNP
Choose the correct answer from the options given below :
1. (1)A, B and C Only
2. (2)B and C Only
3. (3)C and D Only
4. (4)A and D Only
ChemistryJEE Main 4 Apr 2026, Shift 1·Q22·Numerical·Moderate
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Carboxylic acid with bicarbonate
Consider the following sequence of reactions to give the major product (X)
P g of the major product (X) formed is reacted with $\ce{NaHCO3}$ solution to liberate a gas which occupied 11.2 dm $^3$ at STP.
P $=$ g.
(Given molar mass in g mol $^{-1}$ H : 1, C : 12, O : 16, Cl : 35.5)
We corrected a printing error in the original paper
Source printed “ $\ce{NaHCO3}$ soluion”.
ChemistryJEE Main 5 Apr 2026, Shift 1·Q14·MCQ·Tough
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Intramolecular aldol and haloform reaction
“P” is hydrocarbon of molecular formula : $\ce{C8H14}$ . On ozonolysis, “P” forms “Q”. “Q” on treatment with alkali under reflux condition produces. “R”, which on treatment with $\ce{I2}$ /NaOH gives a yellow precipitate. Acidification of the solution gives “S”. The structure of “S” is given below :
The correct structure of “P” is
1. (1)
2. (2)
3. (3)
4. (4)
We corrected a printing error in the original paper
Source printed “The structure of “S” given below”.
ChemistryJEE Main 5 Apr 2026, Shift 2·Q15·MCQ·Easy–moderate
Open
Nitrile hydrolysis and hvz reaction
Complete the following reaction sequence and give the name of major product ‘P'.
1. (1)2-Chloropropanoic acid
2. (2)3-Chloropropanoic acid
3. (3)1-Chloropropane
4. (4)2-Chloropropane
ChemistryJEE Main 5 Apr 2026, Shift 2·Q16·MCQ·Easy–moderate
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Semicarbazone formation and hemiacetal hydrolysis
Given below are two statements :
Statement-I : The condensation reaction between $\ce{CH3-CH=O}$ and under optimum pH will produce
Statement-II : The molecule, will generate $\ce{Ph-CH=O}$ in the presence of dilute acid.
In the light of the above statements, choose the correct answer from the options given below :
1. (1)Both Statement-I and Statement-II are true.
2. (2)Both Statement-I and Statement-II are false.
3. (3)Statement-I is true but Statement-II is false.
4. (4)Statement-I is false but Statement-II is true.
ChemistryJEE Main 6 Apr 2026, Shift 2·Q14·MCQ·Moderate
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Aldol condensation of acetone
‘x' is the product which is obtained by the hydrolysis of prop-1-yne in the presence of mercuric sulphate under dilute acidic medium at 333 K. ‘y' is the product which is obtained by the reaction of ethane nitrile with methyl magnesium bromide in dry ether followed by hydrolysis. IUPAC name of product obtained from ‘x' and ‘y' in the presence of barium hydroxide followed by heating is:
1. (1)2-Methylpent-4-en-3-one
2. (2)4-Methylpent-3-en-2-one
3. (3)4-Methylpent-1-ene
4. (4)2-Methylpent-3-one
ChemistryJEE Main 8 Apr 2026, Shift 2·Q17·MCQ·Moderate
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Selective reduction and lactam hydrolysis
Consider the following reaction.
The major product (P) formed is :
1. (1)
2. (2)
3. (3)
4. (4)
ChemistryJEE Main 8 Apr 2026, Shift 2·Q22·Numerical·Moderate
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Claisen schmidt aldol condensation
‘x' is the product which is obtained from benzene by reacting it with carbon monoxide and hydrogen chloride in the presence of cuprous chloride. ‘y' is the major product obtained from the benzene by reacting it with ethanoyl chloride in the presence of anhydrous $\ce{AlCl3}$ . Product (major) obtained by heating x and y in the presence of alkali is z. Total number of $\pi$ (pi) electrons in z is .