MHT-CET SERIES

Chemistry

Aldehydes Ketones And Carboxylic Acids

66 previous year questions.

Volume: 66 Ques

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Chapter Questions
66 MCQs

PYQ 2007

medium

chemistry ID: mht-cet-

Formalin is the commercial name of

formic acid

fluoroform

aqueous solution of methanal

para formaldehyde

PYQ 2008

medium

chemistry ID: mht-cet-

An ester with molecular formula was treated with excess of and the complex so formed was treated with to give an olefin . Ozonolysis of gave a ketone with molecular formula which shows positive iodoform test. The structure of is

-

PYQ 2009

easy

chemistry ID: mht-cet-

The name of crotonaldehyde is

butenaldehyde

butanal-

but- -en- -al

prop- -en- -ol

PYQ 2009

hard

chemistry ID: mht-cet-

Cannizaro?s reaction is not given by

PYQ 2009

hard

chemistry ID: mht-cet-

Ethyl butyrate has the flavour of which fruit ?

Apple

Pineapple

Orange

Banana

PYQ 2010

medium

chemistry ID: mht-cet-

Ethyl methyl ketone is obtained by heating calcium salts of

formic acid propionic acid

acetic acid propionic acid

acetic acid only

acetic acid methanoic acid

PYQ 2010

medium

chemistry ID: mht-cet-

when reacts with gives a product. The same product is obtained by which reaction ?

Acetic acid methanol

Acetic anhydride water

Acetic anhydride ethanol

Acetamide methanol

PYQ 2014

medium

chemistry ID: mht-cet-

Identify the reagent used in the following reaction. Benzoic acid Benzoyl chloride + Phosphorous oxychloride + Hydrogen chloride

HCl

PYQ 2014

medium

chemistry ID: mht-cet-

Identify the reaction in which carbonyl group of aldehydes and ketones is reduced to methylene group on treatment with hydrazine followed by heating with sodium hydroxide in ethylene glycol.

Wolf-Kishner reduction

Clemmensen reduction

Stephen reaction

Etard reaction

PYQ 2017

medium

chemistry ID: mht-cet-

Which of the following compounds will give positive iodoform test ?

Isopropyl alcohol

Propionaldehyde

Ethylphenyl ketone

Benzyl alcohol

PYQ 2017

medium

chemistry ID: mht-cet-

Aldehydes or ketones when treated with, the product formed is

semicarbazone

phenylhydrazone

hydrazone

oxime

PYQ 2018

medium

chemistry ID: mht-cet-

Which of the following is a tricarboxylic acid?

Citric acid

Malonic acid

Succinic acid

Malic acid

PYQ 2018

medium

chemistry ID: mht-cet-

Which of the following carboxylic acids is most reactive towards esterification?

PYQ 2019

medium

chemistry ID: mht-cet-

Which among the following compounds is obtained when ethane nitrile is acid hydrolysed?

Formic acid

Acetamide

Formamide

Acetic acid

PYQ 2019

medium

chemistry ID: mht-cet-

The number of pi-bonds present in benzoic acid molecule are

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following is a solid trimer of formaldehyde?

Metaldehyde

Paraformaldehyde

Paraldehyde

Trioxane

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following aromatic acids has less acidic strength than benzoic acid?

o - nitrobenzoic acid

p - methoxy benzoic acid

m - nitrobenzoic acid

o - chloro benzoic acid

PYQ 2020

medium

chemistry ID: mht-cet-

Acetoxime on catalytic reduction gives

acetic acid

isopropyl amine

ethyl amine

acetic anhydride

PYQ 2020

medium

chemistry ID: mht-cet-

Identify the product C in the following reaction.

CH CH CH

CH = CH

CH CH NO

CH CH CH OH

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following reactions involves of carboxylic acid?

Gattermann reaction

Riemer-Tiemann reaction

Sandmeyer reaction

Hell-Volhard-Zelinsky reaction

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following is a tricarboxylic acid?

Valeric acid

Oxalic acid

Caproic acid

Citric acid

PYQ 2020

medium

chemistry ID: mht-cet-

0.0210 M solution of is allowed to decompose at . How long will it take to reduce to 0.0150 M? (Given)

5600 s

360.0 s

560.0 s

3364 s

PYQ 2020

medium

chemistry ID: mht-cet-

Which of following reagents is used to avoid further oxidation of aldehydes?

dil.\

PYQ 2020

medium

chemistry ID: mht-cet-

What is the product obtained when ethylamine is heated with large excess of ethyl iodide?

Tetraethyl ammonium iodide

Triethyl amine

Diethyl amine

Ethyl methyl amine

PYQ 2020

medium

chemistry ID: mht-cet-

Identify reducing agent in the following reaction:

O (g)

H O(l)

CH (g)

CO (g)

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following is obtained on dry distillation of equimolar mixture of calcium acetate and calcium propionate?

Ethyl propyl ketone

Propionaldehyde

Acetaldehyde

Ethyl methyl ketone

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following substituent groups increases the acidic strength of aromatic carboxylic acids?

-OH

-CH

-NH

-NO

PYQ 2020

medium

chemistry ID: mht-cet-

Identify the product obtained when 3, 5 - dinitrobenzoic acid is heated with thionyl chloride.

3, 5 - Dinitrobenzyl chloride

3, 5 - Dichlorobenzyl chloride

3, 5 - Dinitrobenzoyl chloride

3 - Chloro - 5 - nitrobenzoic acid

PYQ 2020

easy

chemistry ID: mht-cet-

Which of the following elements is refined by zone refining?

Gallium

Bismuth

Copper

Zinc

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following reactions explains the acidic property of carboxylic acid?

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following is a Wolff-Kishner reduction?

PYQ 2020

medium

chemistry ID: mht-cet-

Which of the following compounds is obtained by dry distillation of calcium propionate?

Pentan-3-one

Pentan-2-one

Propanone

Butan-2-one

PYQ 2020

medium

chemistry ID: mht-cet-

Sodium salt of -halogen carboxylic acid when heated with sodium nitrite and followed by hydrolysis forms

nitroalkane

amine

alcohol

amide

PYQ 2020

medium

chemistry ID: mht-cet-

Which among the following formulae represents glycollic acid?

35

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following substituent groups decreases the acidic strength of aromatic carboxylic acid?$

1

2

3

4

Official Solution

Correct Option: $(1)$

$Step 1: Understanding acidic strength of aromatic carboxylic acids. The acidic strength of aromatic carboxylic acids depends on the stability of the carboxylate ion formed after dissociation. Electron-withdrawing groups stabilize the negative charge on the carboxylate ion and hence increase acidity, while electron-donating groups destabilize it and decrease acidity. Step 2: Effect of substituent groups. Electron-donating groups increase electron density on the aromatic ring and the carboxylate ion, reducing its stability. This leads to a decrease in acidic strength. Electron-withdrawing groups have the opposite effect and increase acidity. Step 3: Analysis of given options. (A) :} This is a strong electron-donating group due to its +M (resonance donating) effect. It destabilizes the carboxylate ion and thus decreases acidic strength. (B) :} This is a strong electron-withdrawing group due to its and effects, which increases acidity. (C) :} Chlorine shows a effect, which increases acidity despite its weak +M effect. (D) :} Nitro group is a very strong electron-withdrawing group, significantly increasing acidic strength. Step 4: Conclusion. Among the given substituents, only the amino group donates electrons strongly and decreases the acidic strength of aromatic carboxylic acids.$

36

PYQ 2020

medium

chemistry ID: mht-cet-

$Which of the following is Rosenmund reduction?$

1

$R=C=N + 2[H] R-CH=NH.HCl R-CHO + NH Cl$

2

$R-CHO + H N-NH R-CH=N-NH RCH + N$

3

$Ar-CO-Cl Ar-CHO + HCl$

4

$R-CO-R + 4[H] R-CH -R + H O$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding Rosenmund Reduction. Rosenmund reduction is a process where acyl chlorides (R-CO-Cl) are reduced to aldehydes (R-CHO) using hydrogen gas in the presence of palladium on barium sulfate (Pd-BaSO) as a catalyst. This reaction selectively reduces the carbonyl group without affecting other parts of the molecule. Step 2: Analyzing the options. (A) R=C=N + 2[H] R-CH=NH.HCl R-CHO + NH Cl:} Incorrect. This is the reaction for the conversion of an isonitrile to an aldehyde, not Rosenmund reduction. (B) R-CHO + H N-NH R-CH=N-NH RCH + N :} Incorrect. This is a reaction for reducing an aldehyde to a primary amine, not Rosenmund reduction. (C) Ar-CO-Cl Ar-CHO + HCl:} Correct. This is the Rosenmund reduction, where acyl chloride is reduced to an aldehyde using hydrogen and Pd-BaSO . (D) R-CO-R + 4[H] R-CH -R + H O:} Incorrect. This is the Clemmensen reduction, not Rosenmund reduction. Step 3: Conclusion. The correct reaction is (C) : Ar-CO-Cl Ar-CHO + HCl, which is the Rosenmund reduction.$

37

PYQ 2020

medium

chemistry ID: mht-cet-

$Which of the following is obtained by catalytic oxidation of ammonia?$

1

$N O$

2

$NO$

3

$HNO$

4

$NO$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding catalytic oxidation of ammonia. The catalytic oxidation of ammonia at high temperatures produces nitrogen monoxide (NO) as the main product. This reaction is important in the production of nitric acid. Step 2: Analyzing the options. (A) N O: This is not the main product of ammonia oxidation. (B) NO: Correct — Nitrogen monoxide (NO) is the main product of catalytic oxidation of ammonia. (C) HNO : This is not the product of catalytic oxidation, but rather formed in other processes. (D) NO : NO is not the direct product of the catalytic oxidation of ammonia. Step 3: Conclusion. The correct answer is (B) NO .$

38

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify B in the following reaction$

1

2

3

4

Official Solution

Correct Option: $(3)$

$Step 1: Identify the reaction type. The given reaction is Stephen reduction, where a nitrile is reduced to an aldehyde using and dilute HCl. Step 2: Formation of intermediate A. The nitrile first forms an iminium salt intermediate. Step 3: Hydrolysis of intermediate. On hydrolysis with, the iminium salt is converted into an aldehyde. Step 4: Conclusion. The final product B formed is an aldehyde, .$

39

PYQ 2020

medium

chemistry ID: mht-cet-

$Which of the following acids does NOT undergo Hell-Volhard-Zelinsky reaction?$

1

$Butanoic acid$

2

$Propanoic acid$

3

$Ethanoic acid$

4

$Methanoic acid$

Official Solution

Correct Option: $(4)$

$Step 1: Recall the condition for HVZ reaction. Hell-Volhard-Zelinsky (HVZ) reaction occurs in carboxylic acids containing at least one -hydrogen atom . The reaction involves -halogenation of the acid. Step 2: Analyze each acid. Butanoic acid: Contains -hydrogen, so it undergoes HVZ reaction. Propanoic acid: Contains -hydrogen, so it undergoes HVZ reaction. Ethanoic acid: Contains -hydrogen, so it undergoes HVZ reaction. Methanoic acid: Does not contain any -carbon or -hydrogen. Step 3: Conclusion. Since methanoic acid lacks an -hydrogen, it does not undergo the HVZ reaction.$

40

PYQ 2020

medium

chemistry ID: mht-cet-

$Which of the following is obtained by hydrogenation of benzoyl chloride in presence of Pd on BaSO ?$

1

$Benzene$

2

$Benzoic acid$

3

$Benzyl alcohol$

4

$Benzaldehyde$

Official Solution

Correct Option: $(4)$

$Step 1: Identify the reaction. Hydrogenation of acid chlorides in the presence of is known as the Rosenmund reduction . Step 2: Apply Rosenmund reduction. In this reaction, an acid chloride is selectively reduced to an aldehyde without further reduction to alcohol. Step 3: Reaction involved. Step 4: Analyze options. (A) Benzene is not formed in this reaction. (B) Benzoic acid is not a reduction product. (C) Benzyl alcohol is not formed due to poisoned catalyst. (D) Benzaldehyde is the correct product. Step 5: Conclusion. Benzaldehyde is obtained by hydrogenation of benzoyl chloride using Pd on BaSO .$

41

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following compounds is treated with benzonitrile to obtain benzophenone in dry ether and then acid hydrolysis?$

1

$CH COCH$

2

$C H MgBr$

3

$C H ONa$

4

$CH MgBr$

Official Solution

Correct Option: $(2)$

$Step 1: Understanding the reaction. In the reaction, benzonitrile reacts with phenyl magnesium bromide (C H MgBr) in dry ether to form benzophenone. The reaction also involves acid hydrolysis to complete the conversion. This is a typical Grignard reaction followed by acid hydrolysis. Step 2: Analyzing the options. (A) CH COCH : Incorrect — This is acetone, not involved in this reaction. (B) C H MgBr: Correct — This is phenyl magnesium bromide, which reacts with benzonitrile to form benzophenone. (C) C H ONa: Incorrect — This is phenoxide, not a suitable reactant in this case. (D) CH MgBr: Incorrect — This is methyl magnesium bromide, which would not form benzophenone. Step 3: Conclusion. The correct answer is (B) C H MgBr, as it is treated with benzonitrile to form benzophenone.$

42

PYQ 2020

medium

chemistry ID: mht-cet-

$Identify product ‘A’ in the following reaction.$

1

$R - CONH$

2

$R - COOH$

3

$R - CHO$

4

$R - CH NH$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding the reaction. The reaction involves the reduction of a nitrile group (C\equivN) using DIBAL-H (diisobutylaluminum hydride), followed by hydrolysis with H O to produce an aldehyde. The nitrile group is reduced to an aldehyde, as seen in the product R - CHO. Step 2: Analyzing the options. (A) R - CONH : This is an amide, not the correct product of the reaction. (B) R - COOH: This is a carboxylic acid, which is not formed in this reaction. (C) R - CHO: Correct — The reduction of nitriles with DIBAL-H followed by hydrolysis forms an aldehyde. (D) R - CH NH : Incorrect — This is an amine, not an aldehyde. Step 3: Conclusion. The correct answer is (C) R - CHO, which is the aldehyde product formed.$

43

PYQ 2020

medium

chemistry ID: mht-cet-

$Which among the following compounds is obtained when calcium formate is dry distilled alone?$

1

$Methanoic acid$

2

$Methanal$

3

$Methanol$

4

$Methoxy methane$

Official Solution

Correct Option: $(2)$

$Step 1: Reaction involved. On dry distillation, calcium salts of carboxylic acids undergo decomposition. Step 2: Specific case of calcium formate. Calcium formate decomposes to give formaldehyde (methanal): Step 3: Conclusion. Thus, methanal is obtained on dry distillation of calcium formate.$

44

PYQ 2022

easy

chemistry ID: mht-cet-

$What is the use of HCl/Sn reagent?$

Official Solution

Correct Option: $(1)$

$The HCl/Sn reagent, also known as hydrochloric acid/tin(II) chloride reagent, is commonly used in organic chemistry for various transformations and reactions. Here are a few examples of its applications: Reduction of Nitro Compounds: HCl/Sn can be used to reduce nitro compounds (compounds containing the -NO 2 group) to their corresponding amines. The reaction is known as the Clemmensen reduction. The nitro group is reduced to an amino group (-NH 2) in the presence of HCl/Sn under reflux conditions. Reduction of Carbonyl Compounds: HCl/Sn can also reduce carbonyl compounds, such as aldehydes and ketones, to their corresponding alcohols. This reaction is called the Clemmensen reduction of carbonyl compounds. The carbonyl group is reduced to a methylene group (-CH 2-) in the presence of HCl/Sn under high-temperature conditions. Dehalogenation Reactions: HCl/Sn can be used to remove halogens from organic compounds through a dehalogenation reaction. For example, it can be used to convert alkyl halides to corresponding hydrocarbons. The tin(II) chloride acts as a reducing agent, and the halogen is replaced with hydrogen. Conversion of Acyl Chlorides to Aldehydes: HCl/Sn reagent can be used to convert acyl chlorides to aldehydes. The tin(II) chloride reacts with the acyl chloride, resulting in the replacement of the chlorine atom with a hydrogen atom. This transformation is useful in the synthesis of aldehydes.$

45

PYQ 2022

easy

chemistry ID: mht-cet-

$Which among the following carboxylic acids is found in Lemon?$

1

$Acetic acid$

2

$Citric acid$

3

$Formic acid$

4

$L-Lactic acid$

Official Solution

Correct Option: $(2)$

46

PYQ 2022

easy

chemistry ID: mht-cet-

$Aldol condensation between which of the following compounds followed by dehydration gives 4-Methylpent-3-en-2-one.$

1

$Two Molecules of CH 3 COCH 3$

2

$Two Molecules of CH 3 CHO$

3

$CH 3 CHO and HCO$

4

$CH 3 CHO and CH COCH$

Official Solution

Correct Option: $(1)$

$The structure of 4-Methylpent-3-en-2-one suggests that it is derived from a pentanone (5-carbon ketone) with a methyl group attached to the fourth carbon and a double bond between the third and fourth carbon. Among the given options, the correct choice is (A) Two molecules of CH 3 COCH 3 (acetone). In this case, acetone (CH 3 COCH 3) acts as both the enol and the carbonyl compound. The aldol condensation between two molecules of acetone can form a β-hydroxy ketone intermediate. Subsequent dehydration of the β-hydroxy ketone will lead to the formation of 4-Methylpent-3-en-2-one. Therefore, the correct choice is (A) Two molecules of CH 3 COCH 3 (acetone).$

47

PYQ 2022

easy

chemistry ID: mht-cet-

$What is IUPAC name of mesityl oxide?$

Official Solution

Correct Option: $(1)$

$The IUPAC name of mesityl oxide is 4-Methyl-3-penten-2-one.$

48

PYQ 2022

easy

chemistry ID: mht-cet-

$Identify the product B in the following reaction. Benzoyl chloride + H 2 O B + HCl$

1

$Benzoic acid$

2

$Benzene$

3

$Acetophenone$

4

$Benzaldehyde$

Official Solution

Correct Option: $(1)$

$Concept: This reaction involves the hydrolysis of an acyl chloride, specifically benzoyl chloride (C₆H₅COCl) . Acyl chlorides are highly reactive derivatives of carboxylic acids and readily undergo hydrolysis when treated with water. Reaction: C₆H₅COCl (benzoyl chloride) + H₂O (water) \to C₆H₅COOH (benzoic acid) + HCl (hydrochloric acid) Step-by-Step Explanation: • Benzoyl chloride contains a reactive acyl group (-COCl). • When water is added, the nucleophilic oxygen in water attacks the electrophilic carbonyl carbon of the acyl chloride. • This leads to the breakdown of the C-Cl bond and the formation of a new C-OH bond, resulting in the formation of benzoic acid . • Chloride ion is released and combines with the hydrogen ion from water to form hydrochloric acid (HCl) . General Reaction for Acyl Chloride Hydrolysis: R-COCl + H₂O \to R-COOH + HCl (In this case, R = C₆H₅) Conclusion: The product B formed when benzoyl chloride is hydrolyzed with water is benzoic acid (C₆H₅COOH) . This is a classical reaction used to prepare benzoic acid in organic chemistry. Therefore, the correct product B is: Benzoic Acid .$

49

PYQ 2022

easy

chemistry ID: mht-cet-

$The first oxidation of a secondary alcohol is?$

Official Solution

Correct Option: $(1)$

$The first oxidation of a secondary alcohol typically results in the formation of a ketone. Secondary alcohols have the general structure R 2 CHOH, where R represents a hydrocarbon group. When a secondary alcohol undergoes oxidation, the alcohol functional group (-OH) is converted into a carbonyl group (C=O) present in a ketone. For example, the oxidation of secondary alcohol is shown below: R 2 CHOH (secondary alcohol) + [O] \to R 2 C=O (ketone) + H 2 O$

50

PYQ 2024

medium

chemistry ID: mht-cet-

$Which of the following is a method for the preparation of benzaldehyde?$

Official Solution

Correct Option: $(1)$

$The Gattermann-Koch reaction is a method for preparing benzaldehyde. It involves the reaction of benzene with carbon monoxide and hydrochloric acid in the presence of a Lewis acid catalyst (such as AlCl3). This reaction introduces an aldehyde group (-CHO) to the benzene ring, forming benzaldehyde. Other methods: - Friedel-Crafts acylation is typically used to form ketones, not aldehydes. - Reduction of benzoic acid leads to benzyl alcohol, not benzaldehyde. - Ozonolysis of styrene produces aldehydes or ketones, but not benzaldehyde specifically. Therefore, the correct answer is the Gattermann-Koch reaction.$

51

PYQ 2024

medium

chemistry ID: mht-cet-

$The Rosenmund reduction involves the reduction of which of the following compounds?$

1

$Carboxylic acid to alcohol$

2

$Aldehyde to alcohol$

3

$Acyl chloride to aldehyde$

4

$Alkene to alkane$

Official Solution

Correct Option: $(3)$

$The Rosenmund reduction is a process used to reduce acyl chlorides to aldehydes. In this reaction, an acyl chloride is treated with hydrogen gas in the presence of a palladium catalyst poisoned by sulfur (such as palladium on barium sulfate). The catalyst helps in the selective reduction of the acyl chloride to an aldehyde while preventing further reduction to an alcohol. Therefore, the correct answer is that the Rosenmund reaction reduces acyl chlorides to aldehydes.$

52

PYQ 2024

easy

chemistry ID: mht-cet-

$The number of -bonds present in benzoic acid is:$

1

$5.$

2

$4.$

3

$7.$

4

$3.$

Official Solution

Correct Option: $(1)$

$Step 1: Structure of benzoic acid. Benzoic acid () consists of: A benzene ring with alternating double bonds (3 -bonds). A carboxylic acid () group attached to the benzene ring. The carboxylic acid group contains: One -bond in the C=O bond. No -bonds in the O-H bond. Step 2: Total number of -bonds. Step 3: Conclusion. The number of -bonds in benzoic acid is 5.$

53

PYQ 2025

medium

chemistry ID: mht-cet-

$Which of the following compounds gives a secondary alcohol upon reaction with methylmagnesium bromide?$

1

$Butyl formate$

2

$3-pentanone$

3

$Pentanal$

4

$Methyl butanoate$

Official Solution

Correct Option: $(3)$

$Methylmagnesium bromide \text{CH}_3\text{MgBr} is a Grignard reagent that adds to carbonyl groups, forming an alcohol. In this case, pentanal, an aldehyde, will react with methylmagnesium bromide to form a secondary alcohol, while the other options will not lead to a secondary alcohol.$

54

PYQ 2025

hard

chemistry ID: mht-cet-

$Which of the following reagents is used in Rosenmund reduction?$

1

$Zn/HCl$

2

$H /Pd - BaSO (poisoned)$

3

$LiAlH$

4

$NaBH$

Official Solution

Correct Option: $(2)$

$The Rosenmund reduction is a chemical reaction used to reduce acyl chlorides to aldehydes. The typical reagent for this reduction is hydrogen gas (H 2) in the presence of a catalyst, specifically palladium (Pd) that is poisoned with barium sulfate (BaSO 4). This specific catalyst combination ensures that the reduction stops at the aldehyde stage and does not proceed further to an alcohol. Let's evaluate the options provided: H 2 /Pd - BaSO 4 (poisoned) : This is indeed the reagent used in the Rosenmund reduction, as it effectively stops at the aldehyde stage. Zn/HCl: This combination is typically used for other types of reductions, such as the reduction of nitro compounds, and is not used in Rosenmund reduction. LiAlH 4 : This is a strong reducing agent used to reduce a wide range of compounds, including esters and amides, to alcohols but not suitable for selective reduction to aldehydes. NaBH 4 : Another reducing agent, commonly used for reducing aldehydes and ketones to alcohols, not used for Rosenmund reduction. Conclusion: The correct reagent for the Rosenmund reduction is H 2 /Pd - BaSO 4 (poisoned) .$

55

PYQ 2026

medium

chemistry ID: mht-cet-

$Which catalyst is used in the Rosenmund Reduction?$

1

$Pd-BaSO$

2

$Ni catalyst$

3

$Pt catalyst$

4

$Cu catalyst$

Official Solution

Correct Option: $(1)$

$Concept: Rosenmund Reduction is an important organic reaction used to convert acid chlorides into aldehydes. The reaction involves hydrogenation of acid chlorides in the presence of a specially poisoned palladium catalyst. Step 1: Understanding the reaction In this reaction, the acid chloride is reduced to an aldehyde. Step 2: Role of the catalyst The catalyst used is palladium deposited on barium sulfate (). The catalyst is often “poisoned” with substances such as sulfur or quinoline to prevent further reduction of the aldehyde to alcohol. Step 3: Importance of poisoning Without poisoning, the aldehyde formed could be further reduced to a primary alcohol. The poisoned catalyst ensures the reaction stops at the aldehyde stage. Conclusion: Thus, the catalyst used in Rosenmund Reduction is Pd-BaSO, commonly known as the Rosenmund catalyst.$

56

PYQ 2026

medium

chemistry ID: mht-cet-

$Which reagent is typically used in Rosenmund reduction to convert acyl chlorides to aldehydes?$

1

2

3

4

Official Solution

Correct Option: $(2)$

$Concept: Rosenmund Reduction is an organic reaction used to convert acid chlorides into aldehydes . In this reaction: • Hydrogen gas is used as the reducing agent. • Palladium catalyst supported on is used. • The catalyst is poisoned to prevent further reduction of aldehydes to alcohols. Step 1: Write the Rosenmund reduction reaction. Step 2: Identify the reagent used. The reagent required is Step 3: State the correct option.$

57

PYQ 2026

medium

chemistry ID: mht-cet-

$Identify the product when a ketone reacts with hydrazine$

1

$Oxime$

2

$Hydrazone$

3

$Semicarbazone$

4

$Phenylhydrazone$

Official Solution

Correct Option: $(2)$

$Concept: Aldehydes and ketones undergo nucleophilic addition-elimination reactions with ammonia derivatives of the type . In these reactions, the nucleophile attacks the carbonyl carbon, followed by the elimination of a water molecule, forming a compound containing a linkage. Step 1: {Identify the reacting reagent.} The given reagent is hydrazine, which is an ammonia derivative. Step 2: {Write the general reaction.} Ketones react with hydrazine in the presence of acid catalyst to form hydrazone: In this reaction: The nucleophile attacks the carbonyl carbon. A molecule of water is eliminated. A double bond is formed. Step 3: {Name the product.} When the group (from hydrazine), the product formed is called a hydrazone . Step 4: {Conclusion.} Therefore, the product formed in this reaction is:$

58

PYQ 2026

easy

chemistry ID: mht-cet-

$What is the IUPAC name for Acetone?$

1

$Propanal$

2

$Propan-1-one$

3

$Propan-2-one$

4

$Butan-2-one$

Official Solution

Correct Option: $(3)$

$Concept: Acetone is the simplest and most common member of the ketone family of organic compounds. Ketones are characterized by the presence of a carbonyl group bonded to two carbon atoms. The molecular formula of acetone is: Its structural formula is: In the IUPAC system of nomenclature, naming is based on the longest carbon chain containing the functional group and the position of that group. Key steps in naming ketones: • Identify the longest carbon chain. • Number the chain so that the carbonyl carbon gets the lowest possible number. • Replace the suffix -ane with -one. Step 1: Identify the carbon chain. Acetone contains three carbon atoms, so the parent hydrocarbon is propane . Step 2: Locate the functional group. The carbonyl group is attached to the second carbon atom. Step 3: Apply the ketone suffix. Replacing -ane with -one gives the name: Thus, the IUPAC name of acetone is Propan-2-one .$

59

PYQ 2026

medium

chemistry ID: mht-cet-

$Which reagent is used in the Stephen reaction to reduce nitriles to imines?$

1

2

3

4

Official Solution

Correct Option: $(2)$

$Concept: The Stephen reduction is a chemical transformation in which nitriles are reduced to imines using a mild reducing agent. The imine formed can subsequently be hydrolyzed to produce aldehydes. This reaction is useful because it allows controlled partial reduction of nitriles without reducing them completely to primary amines. The reagent used in this reaction is stannous chloride in the presence of hydrochloric acid. Step 1: Understanding the role of the reagent. In the Stephen reaction, the nitrile group undergoes reduction by in an acidic medium provided by . The reaction initially produces an iminium salt. Step 2: Formation of aldehyde after hydrolysis. The iminium salt formed in the first step undergoes hydrolysis when treated with water, leading to the formation of an aldehyde. Step 3: Identifying the correct reagent. Among the given options, only performs this controlled reduction of nitriles to imines in the Stephen reaction.$

60

PYQ 2026

hard

chemistry ID: mht-cet-

$What is the IUPAC name for Glyceraldehyde?$

1

$1,2,3-trihydroxypropane$

2

$2,3-dihydroxypropanal$

3

$1,3-dihydroxypropanone$

4

$2-hydroxypropanal$

Official Solution

Correct Option: $(2)$

$Concept: Glyceraldehyde is a simple aldose sugar belonging to the class of monosaccharides . It contains both an aldehyde group and hydroxyl groups. Its molecular formula is: The structural formula can be written as: In IUPAC nomenclature, the aldehyde group has the highest priority and must be assigned carbon number 1. Step 1: Identify the longest carbon chain. The molecule contains three carbon atoms, so the parent chain is propane . Step 2: Identify the functional groups. • Aldehyde group at carbon 1 • Hydroxyl groups at carbons 2 and 3 Step 3: Construct the name. • Two hydroxyl groups dihydroxy • Aldehyde functional group suffix -al Thus, the IUPAC name becomes:$

61

PYQ 2026

easy

chemistry ID: mht-cet-

$What is the IUPAC name for the compound ?$

Official Solution

Correct Option: $(1)$

62

PYQ 2026

easy

chemistry ID: mht-cet-

$Which compound undergoes Cannizzaro reaction?$

1

2

3

4

Official Solution

Correct Option: $(2)$

$Concept: The Cannizzaro reaction is a disproportionation reaction shown by aldehydes that do not contain an -hydrogen atom in the presence of a strong base such as or . In this reaction, one molecule of aldehyde is oxidized to a carboxylate ion, while another molecule is reduced to an alcohol. General reaction: Thus, only aldehydes without -hydrogen undergo Cannizzaro reaction. Step 1: {Check for presence of -hydrogen in each compound.} (Acetaldehyde) contains -hydrogen. (Benzaldehyde) has no -hydrogen . is a ketone, not an aldehyde. is an alcohol. Step 2: {Identify compound suitable for Cannizzaro reaction.} Among the given compounds, only benzaldehyde lacks -hydrogen. Therefore, benzaldehyde undergoes the Cannizzaro reaction. Hence, the correct answer is (B) .$

63

PYQ 2026

easy

chemistry ID: mht-cet-

$What product is formed when a ketone reacts with hydrazine ()?$

Official Solution

Correct Option: $(1)$

64

PYQ 2026

medium

chemistry ID: mht-cet-

$Rosenmund reduction is used to convert acyl chlorides into:$

1

$Alcohols$

2

$Carboxylic acids$

3

$Aldehydes$

4

$Ketones$

Official Solution

Correct Option: $(3)$

$Step 1: Understanding the Question: The question asks about the functional group transformation achieved using the Rosenmund reduction reaction. Step 3: Detailed Explanation: 1. Reaction Description: Rosenmund reduction is a catalytic hydrogenation reaction where an acyl chloride (acid chloride) is selectively reduced. 2. Reagents: The catalyst used is hydrogen gas () over palladium () supported on barium sulfate (). The catalyst is often "poisoned" or partially deactivated with sulfur or quinoline to prevent over-reduction. 3. Chemical Transformation: - The acyl chloride () group is converted into an aldehyde () group. - Without the poisoned catalyst (), the aldehyde would be further reduced to a primary alcohol. Step 4: Final Answer: Rosenmund reduction converts acyl chlorides into aldehydes.$

65

PYQ 2026

medium

chemistry ID: mht-cet-

$Identify the strongest acid among: acetic acid, chloroacetic acid, dichloroacetic acid, and trichloroacetic acid.$

1

$Acetic acid$

2

$Chloroacetic acid$

3

$Dichloroacetic acid$

4

$Trichloroacetic acid$

Official Solution

Correct Option: $(4)$

$Concept: The strength of carboxylic acids increases with the presence of electron-withdrawing groups . These groups stabilize the conjugate base through the inductive effect (effect). Chlorine is a strong electron-withdrawing group. Step 1: Compare the number of chlorine atoms. Acetic acid has no electron-withdrawing substituents. Chloroacetic acid has one chlorine atom. Dichloroacetic acid has two chlorine atoms. Trichloroacetic acid has three chlorine atoms. Step 2: Greater the number of chlorine atoms, stronger the effect and higher the acidity. Thus the acidity order is Step 3: Final result.$

66

PYQ 2026

medium

chemistry ID: mht-cet-

$Which of the following compounds will undergo a Cannizzaro reaction: ?$

1

2

3

4

$Both and$

Official Solution

Correct Option: $(2)$

$Concept: The Cannizzaro reaction occurs in aldehydes that do not contain an -hydrogen atom . Such aldehydes undergo disproportionation in the presence of a strong base to give an alcohol and a carboxylate salt. Step 1: Check for the presence of -hydrogen atoms. Cannizzaro reaction occurs only if -hydrogen is absent. Step 2: Analyze each compound. Acetaldehyde contains -hydrogen atoms, so it does not undergo Cannizzaro reaction. This is a ketone and also contains -hydrogen atoms, so it does not undergo Cannizzaro reaction. Benzaldehyde has no -hydrogen, so it undergoes the Cannizzaro reaction. Step 3: Final result.$

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Aldehydes Ketones And Carboxylic Acids

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