Identify the suitable reagent for the following conversion: <img src="/neet/2025/key__2025-05-0...

Hint: \(LiAlH_4\) can reduce ester to a primary alcohol. Explanation: In this question, an ester is getting reduced to an aldehyde. (i) \(NaBH_4\) is a mild reducing agent, meaning it's effective for reducing aldehydes and ketones but not as reactive as stronger reducing agents like \(LiAlH_4\) It can't reduce esters. (ii) The \(H_2/ Pd-BaSO_4\) catalyst, often used in the Rosenmund reduction, is specifically designed to selectively reduce acid chlorides to aldehydes. The BaSO₄ in this catalyst acts as a poison to prevent over-reduction of the aldehyde to an alcohol. It can't reduce the ester. (iii) When LiAlH 4 reacts with an ester, the hydride ion attacks the carbonyl carbon, leading to the formation of an intermediate. This intermediate then undergoes further reactions, eventually resulting in the cleavage of the ester and the formation of two primary alcohols. (iv) \(AlH(iBu)_2\) is diisobutylaluminium hydride also known as DIBAL-H. It is a bulky reducing agent that acts through an electrophilic mechanism. It coordinates with the carbonyl oxygen, followed by a hydride transfer from the aluminum to the carbonyl carbon. This results in the formation of a hemiacetal intermediate, which then undergoes hydrolysis to yield the aldehyde. The selectivity of DIBAL-H is due to its steric bulk. It doesn't readily attack the aldehyde group further, preventing over-reduction to the alcohol. Hence, option 4 is the correct answer.

The major product of the following reaction is: <img src="/neet/2025/key__2025-05-05_11_50_15_...

Hint : Grignard reagent does nucleophilic addition. The Grignard reagent ( \(CH_3MgBr\) ) is a strong nucleophile. It first attacks the more reactive carbonyl group (ketone). Since it's in excess, it will fully convert the ketone into a tertiary alcohol after the final acidic workup ( \(H_3O^+\) ). The excess Grignard then attacks the nitrile group. One equivalent of \(CH_3MgBr\) adds to the \(C \equiv N\) triple bond to form an imine salt (specifically, a magnesium salt of an imine). Normally, Grignard reagents can add twice to esters or acid chlorides to form alcohols, but they typically add only once to nitriles under these conditions because the resulting imine intermediate is negatively charged and resists further nucleophilic attack. When \(H_3O^+\) is added in the second step: The alkoxide formed at the original ketone site is protonated to an alcohol (-OH). The imine salt at the nitrile site is hydrolyzed into a methyl ketone ( \(-\text{C(=O)CH}_3\) ). This matches the structure in Option 4 , which shows a tertiary alcohol on the left and a new methyl ketone on the right.

Aldehydes Ketones Preparation Properties

01

PYQ 2006

easy

chemistry ID: neet-200

A carbonyl compound reacts with hydrogen cyanide to form cyanohydrins, which form a racemic mixture of \alpha -hydroxy acid on hydrolysis. The carbonyl compound is: 1. Acetaldehyde 2. Acetone 3. Diethyl ketone 4. Formaldehyde

1

(1)

2

(2)

3

(3)

4

(4)

02

PYQ 2006

medium

chemistry ID: neet-200

The self-condensation product of two moles of ethyl acetate in the presence of sodium ethoxide yield is: 1. Ethyl butyrate 2. Acetoacetic ester 3. Methyl acetoacetate 4. Ethyl propionate

1

(1)

2

(2)

3

(3)

4

(4)

03

PYQ 2007

easy

chemistry ID: neet-200

Reduction of aldehydes and ketones into hydrocarbons using amalgam and conc. HCl is called: 1. Clemmensen reduction 2. Cope reduction 3. Dow reduction 4. Wolff-Kishner reduction

1

(1)

2

(2)

3

(3)

4

(4)

04

PYQ 2007

easy

chemistry ID: neet-200

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> A compound with the molecular formula C 5 H 10 that yields acetone on ozonolysis is: 1. 2-Methyl-2-butene 2. 2-Methyl-1-butene 3. Cyclopentane 4. 3-Methyl-1-butene

1

(1)

2

(2)

3

(3)

4

(4)

05

PYQ 2007

easy

chemistry ID: neet-200

The product formed in aldol condensation is: 1. A -hydroxy acid 2. A -hydroxy aldehyde or a -hydroxy ketone 3. An -hydroxy aldehyde or ketone 4. An - unsaturated ester

1

(1)

2

(2)

3

(3)

4

(4)

06

PYQ 2008

easy

chemistry ID: neet-200

\alpha

1

(1)

2

(2)

3

(3)

4

(4)

07

PYQ 2012

easy

chemistry ID: neet-201

The correct order of decreasing acid strength of trichloroacetic acid (A), trifluoroacetic acid (B), acetic acid (C), and formic acid (D) is: 1. B > A > D > C 2. B > D > C > A 3. A > B > C > D 4. A > C > B >D

1

(1)

2

(2)

3

(3)

4

(4)

08

PYQ 2015

easy

chemistry ID: neet-201

The esters that get hydrolyzed most easily under alkaline conditions is? 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

09

PYQ 2016

medium

chemistry ID: neet-201

In the below reaction, the structure of "A" is: 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

10

PYQ 2016

easy

chemistry ID: neet-201

What is the correct order of the carboxylic acids' strength? I. II. III. 1. I > II > III 2. II > III > I 3. III > II > I 4. II > I > III

1

(1)

2

(2)

3

(3)

4

(4)

11

PYQ 2017

easy

chemistry ID: neet-201

A, X, Y, and Z in the above-mentioned reaction are: A X Y Z 1. Methoxy- methane Ethanol Ethanoic acid Semicarbazone 2. Ethanal Ethanol But - 2 - enal semicarbazone 3. Ethanol Acetaldehyde Butanone Hydrazone 4. Methoxy- methane Ethanoic acid Acetate Hydrazine

1

(1)

2

(2)

3

(3)

4

(4)

12

PYQ 2018

easy

chemistry ID: neet-201

The name of the electrophile involved in the below reaction is: 1. Dichloromethyl cation 2. Formyl cation 3. Dichloromethyl anion 4. Dichlorocarbene (:CCl 2)

1

(1)

2

(2)

3

(3)

4

(4)

13

PYQ 2018

easy

chemistry ID: neet-201

Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to: 1. Formation of intramolecular H-bonding 2. Formation of carboxylate ion 3. More extensive association of carboxylic acid via van der waals force of attraction 4. Formation of intermolecular H-bonding

1

(1)

2

(2)

3

(3)

4

(4)

14

PYQ 2021

easy

chemistry ID: neet-202

The intermediate compound 'X' in the following chemical reaction is : 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

15

PYQ 2022

easy

chemistry ID: neet-202

Given below are two statements: Statement I The boiling points of aldehydes and ketones are higher than hydrocarbons of comparable molecular masses because of weak molecular association in aldehydes and ketones due to dipole-dipole interactions. Statement II The boiling points of aldehydes and ketones are lower than the alcohols of similar molecular masses due to the absence of H-bonding. In the light of the above statements, choose the most appropriate answer from the options given below: 1. Statement I is incorrect but Statement II is correct. 2. Both Statement I and Statement II are correct. 3. Both Statement I and Statement II are incorrect. 4. Statement I is correct but Statement II is incorrect.

1

(1)

2

(2)

3

(3)

4

(4)

16

PYQ 2023

easy

chemistry ID: neet-202

Given is a reaction for your reference: The final product [C] is: 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

17

PYQ 2023

easy

chemistry ID: neet-202

Identify the final product [D] obtained in the following sequence of reactions: 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

18

PYQ 2024

easy

chemistry ID: neet-202

Match the reactions listed in List-I with the appropriate reagents or conditions listed in List-II : List-I (Reaction) List-II (Reagents/ Condition) A. I. B. II. C. III. D. IV. Choose the correct answer from the options given below: 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

19

PYQ 2024

easy

chemistry ID: neet-202

Which solution is part of Fehling solution 'A' (used in tests for reducing sugars and aldehydes)? 1. Alkaline copper sulphate 2. Alkaline solution of sodium potassium tartrate (Rochelle's salt) 3. Aqueous sodium citrate 4. Aqueous copper sulphate

1

(1)

2

(2)

3

(3)

4

(4)

20

PYQ 2025

medium

chemistry ID: neet-202

Identify the suitable reagent for the following conversion: 1. (i), (ii) 2. 3. (i), (ii) 4. (i) (ii)

1

(1)

2

(2)

3

(3)

4

(4)

21

PYQ 2025

medium

chemistry ID: neet-202

The major product of the following reaction is: 1. 2. 3. 4.

1

(1)

2

(2)

3

(3)

4

(4)

Aldehydes Ketones Preparation Properties

High-Yield Trend

Questions
21 MCQs

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

1.	A $%5Cbeta$ -hydroxy acid
2.	A $%5Cbeta$ -hydroxy aldehyde or a $%5Cbeta$ -hydroxy ketone
3.	An $%5Calpha$ -hydroxy aldehyde or ketone
4.	An $%5Calpha$ - $%5Cbeta$ unsaturated ester

	A	X	Y	Z
1.	Methoxy- methane	Ethanol	Ethanoic acid	Semicarbazone
2.	Ethanal	Ethanol	But - 2 - enal	semicarbazone
3.	Ethanol	Acetaldehyde	Butanone	Hydrazone
4.	Methoxy- methane	Ethanoic acid	Acetate	Hydrazine

1.	Formation of intramolecular H-bonding
2.	Formation of carboxylate ion
3.	More extensive association of carboxylic acid via van der waals force of attraction
4.	Formation of intermolecular H-bonding

Statement I	The boiling points of aldehydes and ketones are higher than hydrocarbons of comparable molecular masses because of weak molecular association in aldehydes and ketones due to dipole-dipole interactions.
Statement II	The boiling points of aldehydes and ketones are lower than the alcohols of similar molecular masses due to the absence of H-bonding.

1.	Statement I is incorrect but Statement II is correct.
2.	Both Statement I and Statement II are correct.
3.	Both Statement I and Statement II are incorrect.
4.	Statement I is correct but Statement II is incorrect.

1.	$%5Cmathrm%7BHC%5Cequiv%20C%5E-~Na%5E%2B%7D$	2.
3.		4.	$%5Cmathrm%7BC_4H_%7B10%7D%7D$

	List-I (Reaction)		List-II (Reagents/ Condition)
A.		I.
B.		II.	$%5Cmathrm%7BCrO%7D_3$
C.		III.	$%5Cbegin%7Baligned%7D%20%26%20%5Cmathrm%7BKMnO%7D_4%20%5C%5C%20%26%20%5Cmathrm%7BKOH%7D%2C%20%5CDelta%20%5Cend%7Baligned%7D$
D.		IV.	$%5Cmathrm%7B(i)%20%5Cmathrm%7BO%7D_3%5C%5C%20(ii)%20%5Cmathrm%7BZn%7D-%5Cmathrm%7BH%7D_2%20%5Cmathrm%7BO%7D%7D$

1.	$%5Ctext%20%7B%20A-III%2C%20B-I%2C%20C-II%2C%20D-IV%20%7D$
2.	$%5Ctext%20%7B%20A-IV%2C%20B-I%2C%20C-II%2C%20D-III%20%7D$
3.	$%5Ctext%20%7B%20A-I%2C%20B-IV%2C%20C-II%2C%20D-III%20%7D$
4.	$%5Ctext%20%7B%20A-IV%2CB-I%2C%20C-III%2C%20D-II%20%7D$

1.	Alkaline copper sulphate
2.	Alkaline solution of sodium potassium tartrate (Rochelle's salt)
3.	Aqueous sodium citrate
4.	Aqueous copper sulphate

Aldehydes Ketones Preparation Properties

High-Yield Trend

Questions 21 MCQs

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Official Solution

Questions
21 MCQs