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Aldehydes and Ketones MCQs for MDCAT Practice

Chemistry section, Aldehydes and Ketones chapter. Up to eight free sample questions, each with the correct answer and a worked explanation. The full chapter opens in the app.

The bank has 946 active questions on this chapter. Your first 500 practice attempts are free, and every attempt includes a worked explanation.

  1. Question 1
    Fehling's solution works on the principle of redox reaction which results in:
    • Reduction of aldehydes
    • Oxidation of Copper(II)
    • Oxidation of aldehyde (correct answer)
    • Oxidation of Ketone
    Correct answer: C
    Fehling's test identifies aldehydes by their oxidation to carboxylic acids, while the copper(II) in Fehling's solution is reduced to copper(I) oxide.
  2. Question 2
    Which one of the following compounds will give a precipitate of tri-iodomethane (iodoform) when reacted with iodine and aqueous sodium hydroxide?
    • C2H5CHO
    • (CH3)2COH
    • CH3CO2H
    • CH3CH2CH(OH)CH3 (correct answer)
    Correct answer: D
    The iodoform test identifies methyl ketones and secondary alcohols with a methyl group on the alpha carbon, forming a yellow precipitate.
  3. Question 3
    Which of the following will not give iodoform test?
    • Formaldehyde
    • Aceteldehyde (correct answer)
    • Acetone
    • Ethanol
    Correct answer: B
    The iodoform test is specific for methyl ketones and secondary alcohols with a methyl group; formaldehyde, acetone, and ethanol all possess this structural feature.
  4. Question 4
    According to Popoff's Rule for the oxidative cleavage of unsymmetrical ketones, such as 2-hexanone, the carbonyl group remains attached to which alkyl group during the rupture of the C-C bond?
    • The larger alkyl group
    • The smaller alkyl group (correct answer)
    • It distributes equally between both
    • The carbonyl carbon itself is oxidized to CO2
    Correct answer: B
    Popoff's Rule states the carbonyl carbon in unsymmetrical ketones bonds to the smaller alkyl group during oxidative cleavage.
  5. Question 5
    To distinguish aldehyde from ketone which solution is used:
    • Alkaline solution
    • Fehling's solution (correct answer)
    • A solution containing K2Cr2O7
    • A solution containing acid only
    Correct answer: B
    Fehling's solution selectively oxidizes aldehydes to carboxylic acids, forming a red precipitate, while ketones remain unreactive, allowing for distinction.
  6. Question 6
    The haloform test is given by all of the following, except;
    • Formaldehyde (correct answer)
    • Acetaldeyde
    • Acetone
    • Alpha-phenylethyl alcohol
    Correct answer: A
    The haloform test identifies methyl ketones and secondary alcohols with a methyl group. Formaldehyde lacks this crucial structural feature, failing the test.
  7. Question 7
    Ketone can be oxidized by using:
    • Tollen's reagent
    • Fehling solution
    • K2Cr2O7 with H2SO4 (correct answer)
    • K2Cr2O7 with HNO3
    Correct answer: C
    Ketones are resistant to mild oxidation but can be oxidized by strong oxidizing agents like acidified potassium dichromate, unlike aldehydes which are readily oxidized.
  8. Question 8
    Which of the following carbonyl compounds does not shows rapid reaction with sodium nitroprusside
    • Formaldehyde (correct answer)
    • Acetaldehyde
    • Benzaldehyde
    • Acetone
    Correct answer: A
    Sodium nitroprusside reacts with alpha-hydrogens; aldehydes lacking these, like formaldehyde, exhibit slower reaction rates. This highlights steric and electronic effects on carbonyl reactivity.

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