Free Aldehydes and Ketones MCQs with Answers
679 Aldehydes and Ketones MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Aldehydes and ketones contain the polar carbonyl group, but aldehydes are generally more readily oxidised and more reactive than ketones. Coverage includes preparation by oxidation or reduction routes, nucleophilic addition of reagents such as hydrogen cyanide and bisulfite, and tests that distinguish aldehydes from ketones.
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679 questions · page 13 of 34
- A. Rearrangement
- B. Dehydration
- C. Decomposition
- D. All of these options are correct
Explanation: When an aldol product is heated, the primary reaction that occurs is dehydration.
Correct answer: Dehydration- A. Conc HNO3
- B. Tollen's reagent
- C. Benedict's reagent
- D. Fehling's reagent
Explanation: Ketones can be oxidized by the use of dilute HNO3.
Correct answer: Conc HNO3- A. Fehling's solution test
- B. Iodoform test
- C. Tollen's reagent
- D. Benedict's solution test
Explanation: Tollens' reagent is a chemical reagent used to determine the presence of an aldehyde, aromatic aldehyde and alpha-hydroxy ketone…
Correct answer: Tollen's reagent- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: An aldehyde reacts with 2,4-dinitrophenylhydrazine to give a bright, yellow-to-orange crystalline solid called a…
Correct answer: Option D- A. π-bond of C and O
- B. Sigma bond of C and H
- C. Sigma bond of C and O
- D. Sigma bond of C and C
Explanation: The correct answer is the π-bond of C and O. In a carbonyl group, the π-bond is formed by the overlap of p-orbitals from carbon and…
Correct answer: π-bond of C and O- A. A
- B. B
- C. C
- D. D
Explanation: The reaction of formaldehyde with HCN (sodium cyanide and hydrochloric acid) is an example of a nucleophilic addition reaction.
Correct answer: B- A. CH3Cl(CH)2OH
- B. CH3CH2CH2OH
- C. (CH3)3COH
- D. (CH3)3CHOH
Explanation: (B) is a PRIMARY alcohol and would be oxidised to an aldehyde with the same number of carbon atoms.
Correct answer: CH3CH2CH2OH- A. Fehling's test
- B. Benedict's test
- C. Ninhydrin's test
- D. Tollen's test
Explanation: First indication; [Ag(NH3)2]OH is the Tollen's reagent. Second indication; reacts with an aldehyde to form silver (silver mirror test for…
Correct answer: Tollen's test- A. CN-
- B. HCl
- C. Cl
- D. OH
Explanation: CN- breaks away from HCN in a heterolytic manner where CN- gets the lone pair also leaving behind H+.
Correct answer: CN-- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula.
Correct answer: Option C- A. Acetic acid and acid amide
- B. Acetic acid and methyl chloride
- C. Acetic acid and ammonia
- D. Acetic acid and ammonium chloride
Explanation: The acid-catalyzed hydrolysis of a nitrile (CH3CN) first produces an amide, which is then further hydrolyzed to a carboxylic acid (acetic…
Correct answer: Acetic acid and ammonium chloride- A. CH3 ― O ― CH2 ― CH3
- B. CH3 ― CO ― CH2 ― CH3
- C. CH3COCOOH
- D. CH3 ― CH2CHO
Explanation: Ketone has a general formula of R- CO-R, meaning that there are two radical groups surrounding a carbonyl group(C=0).This is shown in…
Correct answer: CH3 ― CO ― CH2 ― CH3- A. Acetone
- B. Acetic acid
- C. Dimethyl ether
- D. Acetaldehyde
Explanation: Acetaldehyde is the product of the described reaction. The oxidation of ethanol with sodium dichromate and dilute sulfuric acid results in…
Correct answer: Acetaldehyde254. The structural formula of the product of reaction of acetone with 2,4-dinitrophenyl hydrazine is:
- A. A
- B. B
- C. C
- D. D
Explanation: The reaction of 2,4- dinitrophenylhydrazine (2,4-DNPH) and acetone in the presence of acid leads to the formation of acetone…
Correct answer: D- A. C2H5COCH3
- B. C2H5CH(CH3)OH
- C. CH3COCH3
- D. C2H5CH2CHO
Explanation: When HCN reacts with a ketone, two new bonds form. The H from HCN adds to 0 in C=O to form C-OH bond and -CN adds to C to form C- CN bond.
Correct answer: C2H5COCH3256. Which group gives a yellow precipitate of triiodomethane when warmed with alkaline aqueous iodine?
- A. An amide group, CH3CONH2
- B. Ethyl ketone group, C2H5COR
- C. A primary alcohol group as in propanol, CH3CH2CH2OH
- D. Methyl ketone group, CH3COR
Explanation: In the case of ethanal, methyl ketone or a secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of…
Correct answer: Methyl ketone group, CH3COR- A. A
- B. B
- C. C
- D. D
Explanation: Structure A represents 1-phenylethanol, which is a secondary alcohol. The alcohol group (-OH) is on a carbon atom that is bonded to a…
Correct answer: A- A. A: CH3CHO
- B. B: CH3COCH3
- C. C: CH3OH
- D. D: HCHO
Explanation: Ketone is a functional group with the structure R2C=O, where R can be a variety of carbon-containing substituent
Correct answer: B: CH3COCH3- A. Formation of H2O
- B. Release of H2 gas
- C. Brick red precipitate
- D. Yellow crystal
Explanation: The formation of yellow crystals is an appropriate indication of a positive iodoform test.
Correct answer: Yellow crystal- A. Propionaldehyde
- B. Methanone
- C. Acetaldehyde
- D. Methanal
Explanation: Methanal/formaldehyde is a naturally occurring organic compound with the formula CH₂O and structure H−CHO.
Correct answer: Methanal