Nomenclature and Structure of Aldehydes and Ketones

Nomenclature and Structure of Aldehydes and Ketones MDCAT MCQs with answers

8 past paper MCQs on Nomenclature and Structure of Aldehydes and Ketones, from the Aldehydes and Ketones unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.Which of the following is the correct name of $\mathrm{CH_3CH_2CH_2COCH_2CHO}$? (MDCAT 2022)

  1. 3-oxohexanal
  2. 3-onehexanal
  3. 3-oxohexanone
  4. hexanedial
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Correct answer: (a) 3-oxohexanal

The aldehyde takes the suffix and is carbon 1, so the ketone at carbon 3 is named as an oxo prefix.

2.$\mathrm{C_nH_{2n}O}$ is the general formula of: (MDCAT 2024)

  1. ethers
  2. carboxylic acids
  3. ketones
  4. carbolic acid
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Correct answer: (c) ketones

Aldehydes and ketones share this formula; of the options only the ketones fit.

3.Formalin is a mixture of: (NUMS MDCAT 2025)

  1. 40% HCHO, 8% CH3OH, 52% H2O
  2. 40% CH3CHO, 8% CH3OH, 50% H2O
  3. 40% CH3CHO, 8% C2H5OH, 50% H2O
  4. 45% HCHO, 8% C2H5OH, 50% H2O
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Correct answer: (a) 40% HCHO, 8% CH3OH, 52% H2O

Formalin is the $40\%$ aqueous solution of formaldehyde, with a little methanol to stop it polymerizing.

4.Q.115 Which of the following is the correct name of CH3CH2CH2COCH2CHO? (UHS MDCAT 2023)

  1. 3-oxo hexanal
  2. 3-one hexanal
  3. 3-oxo hexanol
  4. 3- keto hexanol
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Correct answer: (a) 3-oxo hexanal

The aldehyde is the senior group, so the chain is hexanal with the ketone named as a 3-oxo substituent.

5.Q.119 If carboxylic acid and ketone groups C=O are present in a chain then final name will be given as (UHS MDCAT 2023)

  1. oxo, oic acid
  2. one, oic acid
  3. Both 1 and 2
  4. None of these
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Correct answer: (a) oxo, oic acid

The acid takes the suffix and the ketone is named as an oxo substituent.

6.What is the ILIPAC name of diisopropyi ketone? (UHS MDCAT 2023)

  1. 1,3-Dilsopropylpropan-2-one
  2. 2,4-Dimethylpentan-3-one
  3. 2,4-Dimethylpentan-2-one
  4. 1,3-Dimethylpropan-2-one
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Correct answer: (b) 2,4-Dimethylpentan-3-one

The longest chain is pentane with the carbonyl at C3 and a methyl on C2 and C4.

7.Aldehyde common names are derived from carboxylic acid names with the same number of: (PMC MDCAT 2022)

  1. Hydrogen atoms
  2. Carbon atoms
  3. Oxygen atoms
  4. Carbon and hydrogen atoms
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Correct answer: (b) Carbon atoms

Formaldehyde is named from formic acid, acetaldehyde from acetic acid, and so on.

8.The carbonyl compound which is attached with at least one H atom at one side is called as? (PMC Practice 2021)

  1. Ketones
  2. Aldehydes
  3. Ethers
  4. Alkyl halides
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Correct answer: (b) Aldehydes

An aldehyde has at least one hydrogen on the carbonyl carbon; a ketone has two alkyl groups.

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