The chapter on Aldehydes, Ketones, and Carboxylic Acids in CBSE Class 12 Chemistry focuses on organic compounds with these functional groups. It covers their properties, reactions, and interconversions. This chapter is important and carries 8 marks in the annual assessment for the 2023-24 session, so students need to understand all the concepts well. This article provides a set of important multiple-choice questions (MCQs) for effective revision, in line with the revised CBSE syllabus and the latest NCERT Book.
Practicing with CBSE Class 12 Chemistry MCQs for Aldehydes, Ketones, and Carboxylic Acids is a great way to test your understanding and clear up any confusion about complex topics. Below, you’ll find a set of CBSE Class 12 Chemistry MCQs for Aldehydes, Ketones, and Carboxylic Acids with answers, which you can also download from the provided link.
Aldehydes, ketones, carboxylic acids, and their derivatives are organic compounds with carbonyl groups. In formaldehyde, the simplest aldehyde, the carbonyl carbon is bonded to two hydrogen atoms. In other aldehydes, the carbonyl carbon is bonded to a hydrogen atom and an alkyl group. In ketones, the carbonyl carbon is bonded to two alkyl groups. Carboxylic acids are formed by the oxidation of primary alcohols or aldehydes, and can also be made from nitriles, acid chlorides, esters, anhydrides, and amides through hydrolysis.
Also Check: Important Questions for Class 12 Chemistry Chapter 12 Aldehydes, Ketones and Carboxylic Acids
Aldehydes, ketones, and carboxylic acids all have a carbonyl group with a double bond between carbon and oxygen. This group has sp2 hybridization, with one sigma bond and one pi bond. The electron cloud is above and below the plane of the bond. Due to oxygen’s higher electronegativity, the carbonyl group is polar.
Aldehydes: Aldehydes have one hydrogen atom, one alkyl or aryl group, and one carbonyl group.
Ketones: Ketones have a carbonyl group linked to two alkyl or aryl groups.
Carboxylic Acids: Carboxylic acids have a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (OH). The carbon atom is also bonded to a hydrogen atom or another univalent group. The carboxyl group (COOH) consists of a carbonyl (C=O) and a hydroxyl group.
For effective revision, practicing with CBSE Class 12 Chemistry MCQs for Aldehydes, Ketones, and Carboxylic Acids is crucial. These MCQs help in analyzing your understanding and eliminating any doubts related to this chapter.
Ques. Formic acid and formaldehyde can be distinguished by treating with:
(a) Benedict’s solution
(b) Tollens’ reagent
(c) Fehling’s solution
(d) NaHCO3
Answer: (d) NaHCO3
Ques. Oxidation of cyclohexene using acidified KMnO4 will give:
(a) adipic acid
(b) hexane-1,6-dial
(c) cyclohexane carboxylic acid
(d) cyclopentane carboxylic acid
Answer: (a) adipic acid
Ques. Which aldehyde will give Cannizzaro’s reaction?
(a) CH3CH2CH2CHO
(b) CH3CH2CHCHO
(c) (CH3)3CCHO
(d) (CH3)2CH2CH2CHO
Answer: (c) (CH3)3CCHO
Ques. Methyl magnesium bromide on reaction with SO2 followed by hydrolysis gives:
(a) methyl sulphonic acid
(b) methane sulphinic acid
(c) dithio acetic acid
(d) ethanethiol
Answer: (b) methane sulphinic acid
Ques. Which of the following is not a fatty acid?
(a) Stearic acid
(b) Palmitic acid
(c) Propionic acid
(d) Phenyl acetic acid
Answer: (d) Phenyl acetic acid
Ques. Which of the following orders of relative strengths of acids is correct?
(a) ClCH2COOH > FCH2COOH > BrCH2COOH
(b) ClCH2COOH > BrCH2COOH > FCH2COOH
(c) BrCH2COOH > ClCH2COOH > FCH2COOH
(d) FCH2COOH > ClCH2COOH > BrCH2COOH
Answer: (d) FCH2COOH > ClCH2COOH > BrCH2COOH
Ques. The formation of cyanohydrin from a ketone is an example of:
(a) Electrophilic addition
(b) Nucleophilic addition
(c) Nucleophilic substitution
(d) Electrophilic substitution
Answer: (b) Nucleophilic addition
Ques. When acetaldehyde is heated with Fehling’s solution, it gives a red precipitate of:
(a) Cu
(b) CuO
(c) CuSO4
(d) Cu2O
Answer: (d) Cu2O
Also Check: Physical Properties of Aldehydes and Ketones
Ques. Which is the most suitable reagent for the following conversion?
CH3-CH=C(CH3)-CO-CH3 → CH3-CH=C(CH3)-COO-
(a) Tollen’s reagent
(b) Benzoyl peroxide
(c) I2 and NaOH solution
(d) Sn and NaOH solution
Answer: (c) I2 and NaOH solution
Ques. When benzaldehyde and formaldehyde are heated in an aqueous NaOH solution, they produce:
(a) sodium formate + benzyl alcohol
(b) methanol + sodium benzoate
(c) methanol + benzyl alcohol
(d) sodium formate + sodium benzoate
Answer: (a) sodium formate + benzyl alcohol
Ques. Ketones react with Mg-Hg over water to give:
(a) alcohols
(b) pinacols
(c) pinacolones
(d) none of these
Answer: (b) pinacols
Ques. Which of the following hydrogens is the most acidic?
(a) hexane-2,4-dione
(b) hexane-2,3-dione
(c) hexane-2,5-dione
(d) hexane-3-one
Answer: (a) hexane-2,4-dione
Ques. Acetone is mixed with bleaching powder to give:
(a) Ethanol
(b) Acetaldehyde
(c) Chloroform
(d) Phosgene
Answer: (c) Chloroform
Ques. Propionic acid with Br2/P yields a dibromo product. Its structure would be:
(a) CH2BrCH2COBr
(b) CH2BrCHBrCOOH
(c) CHBr2CH2COOH
(d) CH3CBr2COOH
Answer: (d) CH3CBr2COOH
Ques. The reaction in which hydrocarbons are formed when aldehydes and ketones are reduced with amalgamated zinc and conc. HCl is called:
(a) Dow reduction
(b) Clemensen’s reduction
(c) Cope reduction
(d) Wolff-Kishner reduction
Answer: (b) Clemensen’s reduction
Ques. What is the common name of the molecule with a CHO group connected to a benzene ring’s sp2 hybridized carbon?
(a) Benzaldehyde
(b) Phthalaldehyde
(c) Both a and d
(d) None of these
Answer: (a) Benzaldehyde
Ques. Determine the IUPAC name for CH3-CH=CH-CHO:
(a) But-2-enal
(b) Ethane
(c) But-2-en
(d) Buten-2-al
Answer: (a) But-2-enal
Also Check: Aldehydes and Ketones
Ques. What is butanal’s common name?
(a) n-Butyraldehyde
(b) Butanaldehyde
(c) Butyraldehyde
(d) None of these
Answer: (a) n-Butyraldehyde
Ques. Which of the following ketones has the common term acetone?
(a) Dimethyl ketone
(b) Ethyl methyl ketone
(c) Diethyl ketone
(d) N-propyl ketone
Answer: (a) Dimethyl ketone
Ques. When all of the following are present in a compound, which one will be the major group?
(a) -CHO
(b) -CO–
(c) -Cl–
(d) -OH
Answer: (a) -CHO
Ques. What is the number of carbon atoms in formaldehyde?
(a) Null
(b) 1
(c) Two
(d) Three
Answer: (b) 1
Ques. What is diisopropyl ketone’s IUPAC name?
(a) 1,3-Isopropyl propan-2-one
(b) 2,4-Dimethylpentan-3-one
(c) 2-Methyl-1-(1-methylethyl)propan-1-one
(d) 1,3-Dimethylpropan-2-one
Answer: (b) 2,4-Dimethylpentan-3-one
Ques. What is the angle between the carbonyl C-O bond and the bond between the carbonyl carbon and the atom connected to it?
(a) 60 degrees
(b) 90 degrees
(c) 120 degrees
(d) 135 degrees
Answer: (c) 120 degrees
Ques. What is -Methylcyclohexanone’s correct IUPAC name?
(a) Methylcyclohexanone
(b) Methylcyclohexan-2-one
(c) 2-Methylcyclohexanone
(d) Cyclo Methyl Hexan-2-one
Answer: (c) 2-Methylcyclohexanone
Ques. Which of the following compounds doesn’t have a carbonyl group in it?
(a) Alcoholic beverages
(b) Aldehyde
(c) The ketones
(d) Carboxylic acid
Answer: (a) Alcoholic beverages
Ques. ________ is another name for the chemical 3-Phenylprop-2-enal.
(a) Crotonaldehyde
(b) Cinnamaldehyde
(c) Salicylaldehyde
(d) Vanillin
Answer: (b) Cinnamaldehyde
Ques. What is the number of aldehydic groups in the chemical phthalaldehyde?
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (b) 2
Ques. Ethyl formate reacts with an excess of CH3MgI and then hydrolyzes to produce:
(a) Ethanol
(b) n-Propyl alcohol
(c) Propanal
(d) Isopropyl alcohol
Answer: (d) Isopropyl alcohol
Ques. The development of a new C-C bond is conceivable in:
(a) Reaction of Cannizzaro
(b) Friedel-Crafts reaction
(c) Clemmensen reduction
(d) Reimer-Tiemann reaction
Answer: (b) Friedel-Crafts reaction, (d) Reimer-Tiemann reaction
Ques. Which of the following methods cannot produce aldehydes?
(a) Oxidation of primary alcohols
(b) Dehydrogenation of secondary alcohols
(c) Ozonolysis of alkenes
(d) Hydration of ethyne with acid
Answer: (b) Dehydrogenation of secondary alcohols
Ques. Which of the following reactions can produce ketones?
(a) Oxidation of primary alcohols
(b) Dehydrogenation of primary alcohols
(c) Dehydrogenation of tertiary alcohols
(d) Oxidation of secondary alcohols
Answer: (d) Oxidation of secondary alcohols
Ques. Conversion of propyne to acetone requires three important reagents. Identify which of the following is not one of the three?
(a) Water
(b) Zinc dust
(c) H2SO4
(d) HgSO4
Answer: (b) Zinc dust
Ques. What is the catalyst used in the hydrogenation of acetyl chloride to produce ethanal?
(a) Pt over BaSO4
(b) Pt over CuSO4
(c) Pd over BaSO4
(d) Pd over CuSO4
Answer: (c) Pd over BaSO4
Ques. Which of the following carbonyl compounds can be prepared from Rosenmund reaction?
(a) Methanal
(b) Acetone
(c) Butanone
(d) Benzaldehyde
Answer: (d) Benzaldehyde
Ques. Which of the following is required in Stephen reaction?
(a) LiCl
(b) NiCl2
(c) SnCl2
(d) TiCl4
Answer: (c) SnCl2
Ques. Which of the following compounds helps in reducing esters to aldehydes?
(a) BINAL-H
(b) DIBAL-H
(c) DIPT
(d) TBAF
Answer: (b) DIBAL-H
