An organic compound “P” of molecular formula 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 :

Compound P (C6H12O3) gives a positive iodoform test, indicating it has a methyl ketone group (CH3CO-). It gives a negative Tollen's test, indicating no free aldehyde group. On acidic hydrolysis, P yields Q. Compound Q gives both positive iodoform test and Tollen's test, meaning Q contains both a methyl ketone and an aldehyde group. Looking at the options, if P is an acetal of an aldehyde, acidic hydrolysis will regenerate the aldehyde. Option 2 is CH3-CO-CH2-CH(OCH3)2 (an acetal of aldehyde). This compound 'P' has a CH3CO- group (positive iodoform) and an acetal (protected aldehyde, negative Tollen's). On hydrolysis: The product Q (CH3-CO-CH2-CHO) has a methyl ketone (positive iodoform test) and an aldehyde (positive Tollen's test). Whenever an aldehyde test becomes positive *after* hydrolysis, it points to a protected aldehyde, usually an acetal or hemiacetal. A compound with molecular formula Cn H2n O3 often represents a keto-acetal. Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids Class 12 Chemistry: Alcohols, Phenols and Ethers

An organic compound “P” of molecular formula 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 :

Compound P (C6H12O3) gives a positive iodoform test, indicating it has a methyl ketone group (CH3CO-). It gives a negative Tollen's test, indicating no free aldehyde group. On acidic hydrolysis, P yields Q. Compound Q gives both positive iodoform test and Tollen's test, meaning Q contains both a methyl ketone and an aldehyde group. Looking at the options, if P is an acetal of an aldehyde, acidic hydrolysis will regenerate the aldehyde. Option 2 is CH3-CO-CH2-CH(OCH3)2 (an acetal of aldehyde). This compound 'P' has a CH3CO- group (positive iodoform) and an acetal (protected aldehyde, negative Tollen's). On hydrolysis: The product Q (CH3-CO-CH2-CHO) has a methyl ketone (positive iodoform test) and an aldehyde (positive Tollen's test). Whenever an aldehyde test becomes positive *after* hydrolysis, it points to a protected aldehyde, usually an acetal or hemiacetal. A compound with molecular formula Cn H2n O3 often represents a keto-acetal. Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids Class 12 Chemistry: Alcohols, Phenols and Ethers

An organic compound “P” of molecular formula C6H12O3 gives positive Iodoform test but negative Tollen’s test. When “P”…

Year	2026	2025	2024	Total
Questions	14	21	11	46

Year

2026

2025

2024

Total

Questions

Solution & Explanation

Core Logic

Compound P ( $C₆H₁₂O₃$ $C_6H_{12}O_3$) gives a positive iodoform test, indicating it has a methyl ketone group ( $CH₃CO-$ $CH_3CO-$). It gives a negative Tollen's test, indicating no free aldehyde group.

On acidic hydrolysis, P yields Q. Compound Q gives both positive iodoform test and Tollen's test, meaning Q contains both a methyl ketone and an aldehyde group.

Looking at the options, if P is an acetal of an aldehyde, acidic hydrolysis will regenerate the aldehyde. Option 2 is $CH₃-CO-CH₂-CH(OCH₃)₂$ $\mathrm{CH_3-CO-CH_2-CH(OCH_3)_2}$ (an acetal of aldehyde). This compound 'P' has a $CH₃CO-$ $CH_3CO-$ group (positive iodoform) and an acetal (protected aldehyde, negative Tollen's). On hydrolysis:

CH₃-CO-CH₂-CH(OCH₃)₂ H₂O/H^+ CH₃-CO-CH₂-CHO + 2CH₃OH

The product Q ( $CH₃-CO-CH₂-CHO$ $\mathrm{CH_3-CO-CH_2-CHO}$) has a methyl ketone (positive iodoform test) and an aldehyde (positive Tollen's test).

Chemical Reactions of Aldehydes and Ketones diagram for Q61 - JEE Main 2026 Morning

Pattern Recognition

Whenever an aldehyde test becomes positive after hydrolysis, it points to a protected aldehyde, usually an acetal or hemiacetal. A compound with molecular formula $Cₙ H₂ₙ O₃$ $C_n H_{2n} O_3$ often represents a keto-acetal.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids Class 12 Chemistry: Alcohols, Phenols and Ethers

More Aldehydes, Ketones and Carboxylic Acids Previous-Year Questions — Page 10

Q jee_main_2024_31_jan_morning Reactions with Grignard Reagent

The product of the following reaction is P.

Reactions with Grignard Reagent diagram for Q84 - JEE Main 2024 Morning — The image shows p-hydroxybenzaldehyde reacting with one equivalent of PhMgBr followed by aqueous ammonium chloride.

The number of hydroxyl groups present in the product P is

Numerical Answer. Answer: 0 to 0

Solution

Core Logic

The given reactant is p-hydroxybenzaldehyde, which contains both a phenolic $-OH$ $-OH$ group (acidic) and an aldehyde group (electrophilic).

When one equivalent of Grignard reagent ( $PhMgBr$ $PhMgBr$) is added, it behaves primarily as a strong base due to the presence of an acidic proton. Acid-base reactions are extremely fast compared to nucleophilic additions.

The acidic phenolic $-OH$ $-OH$ reacts with $PhMgBr$ $PhMgBr$:

PhMgBr + HO-C₆H₄-CHO arrow Ph-H (Benzene) + BrMg-O-C₆H₄-CHO

Upon workup with $aq. NH₄Cl$ $aq. NH_4Cl$, the phenoxide ion simply regenerates the starting p-hydroxybenzaldehyde. However, the question asks for the number of hydroxyl groups present in the formed product (Benzene).

The distinct product formed in the reaction is Benzene. Benzene has 0 hydroxyl groups.

Pattern Recognition

Whenever a Grignard reagent encounters a molecule with an acidic hydrogen (alcohol, phenol, amine, alkyne), it will invariably act as a base first. If only 1 equivalent is used, nucleophilic addition to carbonyls will NOT happen.

Chapter Mix

Class 12 Chemistry: Aldehydes, Ketones and Carboxylic Acids Class 12 Chemistry: Alcohols, Phenols and Ethers

An organic compound “P” of molecular formula $C₆H₁₂O₃$ $C_{6}H_{12}O_{3}$ 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 :

Solution & Explanation

Core Logic

Pattern Recognition

Chapter Mix

Reference Study Guides

More Aldehydes, Ketones and Carboxylic Acids Previous-Year Questions — Page 10

Solution

Core Logic

Pattern Recognition

Chapter Mix

More Aldehydes, Ketones and Carboxylic Acids Questions — jee_main_2026_21_jan_morning

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An organic compound “P” of molecular formula C₆H₁₂O₃$C_{6}H_{12}O_{3}$ 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 :

Solution & Explanation

Core Logic

Pattern Recognition

Chapter Mix

Reference Study Guides

More Aldehydes, Ketones and Carboxylic Acids Previous-Year Questions — Page 10

Solution

Core Logic

Pattern Recognition

Chapter Mix

More Aldehydes, Ketones and Carboxylic Acids Questions — jee_main_2026_21_jan_morning

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