Free Reactivity of Aldehydes and Ketones MCQs with Answers
83 Reactivity of 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.
The polar carbonyl group makes aldehydes and ketones undergo nucleophilic addition, reduction and condensation reactions. Aldehydes are generally more reactive and oxidise readily to carboxylic acids, whereas ketones resist mild oxidation; reactions with hydrogen cyanide, sodium bisulfite and 2,4-DNP help identify their behaviour.
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- A. Green
- B. Brown
- C. Magenta
- D. Red
Explanation: Brady's reagent (2,4-dinitrophenylhydrazine) reacts with the carbonyl group of benzaldehyde.
Correct answer: Red- A. Because water reacts violently with LiAlH4
- B. Because water will protonate LiAlH4
- C. Because water inhibits the process
- D. Because it will result to alkenes
Explanation: This is the correct option. LiAlH₄ is a highly reactive reducing agent.
Correct answer: Because water reacts violently with LiAlH4- A. Aldol condensation
- B. Cannizzaro's reaction
- C. lodoform test
- D. Lucas test
Explanation: Iodoform test, as it specifically distinguishes between ethanal and propanal by their reactions with iodine and hydroxide ions to form or…
Correct answer: lodoform test- A. Reducing property.
- B. Oxidizing property.
- C. Neutralizing ability.
- D. Redox property.
Explanation: Aliphatic aldehydes form a brick-red precipitate with Fehling's solution. To an aldehyde solution, add Fehling's solution and boil.
Correct answer: Redox property.- A. Acetone
- B. Acetic acid
- C. Ethanol
- D. Ether
Explanation: Acetone is the correct answer. It is a solvent that effectively dissolves nail polish, making it easy to remove.
Correct answer: Acetone- A. Acetone
- B. Acetic acid
- C. Acetamide
- D. Acetic anhydride
Explanation: The reaction given is iodoform reactionAcetic acid, acetamide and acid anhydride don't undergo iodoform reaction
Correct answer: Acetone- A. Formaldehyde
- B. Aceteldehyde
- C. Acetone
- D. Ethanol
Explanation: Formaldehyde does not have a methyl group adjacent to a carbonyl group, which is necessary for the iodoform reaction to occur.
Correct answer: Aceteldehyde- A. Option A: Gem diol with no electron-withdrawing groups
- B. Option B: Gem diol with a weak electron-withdrawing group
- C. Option C: Gem diol with a strong electron-withdrawing group
- D. Option D: Gem diol with a bulky substituent
Explanation: The stability of a geminal diol is significantly influenced by the presence of electron-withdrawing groups attached to the carbon that…
Correct answer: Option C: Gem diol with a strong electron-withdrawing group- A. 2, 4 - DNPH
- B. Iodine in NaOH
- C. Sodium nitroprusside
- D. hydrogen cyanide
Explanation: Iodoform test (I₂ / NaOH) is the correct reagent for distinguishing methyl ketones
Correct answer: Iodine in NaOH- A. CH3CH2CH3CH3CHO
- B. CH3CH2CH2COCH3
- C. CH3CH2CH(CH3)CHO
- D. CH3CH2COCH2CH3
Explanation: b) CH3CH2CH2COCH3:This compound is 2-pentanone, which is a ketone with the molecular formula C5H10O.
Correct answer: CH3CH2CH2COCH3- A. Acetaldehyde
- B. Acetone
- C. Aldehydes
- D. Alkene
Explanation: NaBH4 cannot reduce alkenes into alkanes because in a C=C there is no nucleophilic nature, the H- ion needs a positive carbon to attack…
Correct answer: Alkene- A. Aldol condensation reaction
- B. Cannizaro reaction
- C. Clemenson condensation reaction
- D. Wolfkishner reaction
Explanation: According to PTB page 237, 50% concentrated NaOH solution is generally used in Cannizaro reaction as it is used for aldehydes which do not…
Correct answer: Cannizaro reaction- A. Formaldehyde
- B. Acetaldehyde
- C. Acetone
- D. Butanone
Explanation: The Cannizzaro reaction is basically a chemical reaction which involves the base-induced disproportionation of an aldehyde lacking a…
Correct answer: Formaldehyde- A. Butanal
- B. Methanal
- C. Ethanal
- D. All of these
Explanation: Option A: Butanal, also known as butyraldehyde, is an aldehyde with the chemical formula C4H8O.
Correct answer: All of these- A. Acetaldehyde
- B. 3-hexanone
- C. Butanone
- D. Acetone
Explanation: 3-hexanone does not give the iodoform test. The iodoform test is a chemical test used to detect the presence of methyl ketones.
Correct answer: 3-hexanone- A. Nucleophilic
- B. Electrophilic
- C. Neutral
- D. All of these options are correct
Explanation: The carbon present in aldehyde is electrophilic. An electrophile is a molecule or ion that has a partial positive charge and is attracted…
Correct answer: Electrophilic- A. Ketones
- B. Hydrocarbons
- C. Alcohols
- D. Ethers
Explanation: Grignard reagent,R-Mg-X, reacts with carbonyl group in aldehydes to give secondary alcohols with the exception of methanal which gives…
Correct answer: Alcohols- A. Propanone
- B. 3-Propanone
- C. 2-Butanone.
- D. 2-Propanone.
Explanation: "Propane-2-one," tells us that acetone is a compound with a three-carbon chain (propane) and a ketone functional group (-C=O) on the…
Correct answer: 2-Propanone.- A. Alkenes
- B. Alkanes
- C. Alkynes
- D. Alcohols
Explanation: Option B is correct since the reduction of aldehydes and ketones to alkanes is done in Wolff Krishner's reaction.
Correct answer: Alkanes- A. Phenols
- B. Acetone
- C. Ethanal
- D. Methanol
Explanation: Positive iodoform test is given by a methyl ketone or a secondary alcohol with a methyl group in the alpha position.
Correct answer: Ethanal