Carboxylic Acids

Carboxylic Acids MDCAT MCQs with answers

59 past paper MCQs from Chemistry unit 18, Carboxylic Acids, across 3 topics. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

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Nomenclature, Structure and Preparation of Carboxylic Acids

1.The hydrolysis of nitriles produces: (MDCAT 2020)

  1. carboxylic acids
  2. aldehydes
  3. ketones
  4. esters
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Correct answer: (a) carboxylic acids

$\mathrm{RCN+2H_2O\to RCOOH+NH_3}$, which is one of the standard preparations of an acid.

2.When carboxylic acids and dicarboxylic acids have similar molecular weights, how do their melting points compare? (MDCAT 2022)

  1. carboxylic acids have greater melting points
  2. dicarboxylic acids have greater melting points
  3. both acids have similar melting points
  4. there is no consistent pattern
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Correct answer: (b) dicarboxylic acids have greater melting points

Two carboxyl groups make more hydrogen bonds and pack better, so more heat is needed to break the crystal up.

3.If both carboxylic acid and ketone $\mathrm{C{=}O}$ groups are present in a chain, then the final name will be given as: (MDCAT 2022)

  1. oxo...oic acid
  2. one...oic acid
  3. al...oic acid
  4. none of these
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Correct answer: (a) oxo...oic acid

The acid outranks the ketone, so the acid takes the suffix and the ketone becomes an oxo prefix.

All 22 Nomenclature, Structure and Preparation of Carboxylic Acids MCQs → Nomenclature, Structure and Preparation of Carboxylic Acids notes →

Reactivity of Carboxylic Acids

4.Which among the following has the least pH? (MDCAT 2022)

  1. $\mathrm{CH_3CH_2COOH}$
  2. $\mathrm{CH_2ClCH_2COOH}$
  3. $\mathrm{CH_3CHClCOOH}$
  4. $\mathrm{CH_3CH_2CH_2COOH}$
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Correct answer: (c) $\mathrm{CH_3CHClCOOH}$

The chlorine on the carbon next to the carboxyl group pulls electrons away most strongly, so this acid is the strongest and its pH the lowest.

5.Acetic acid is a weaker acid than sulphuric acid because of which of the following reasons? (MDCAT 2023)

  1. it decomposes on increasing temperature
  2. it has less degree of ionisation
  3. it has a $-\mathrm{COOH}$ group
  4. it has a greater inductive effect
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Correct answer: (b) it has less degree of ionisation

Only a small fraction of its molecules ionize in water, so the concentration of $\mathrm{H^+}$ it gives is far lower.

6.Carboxylic acid reacts with metal carbonate. The colorless gas evolved is: (NUMS MDCAT 2025)

  1. H2
  2. O2
  3. CO2
  4. CO
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Correct answer: (c) CO2

A carboxylic acid displaces carbon dioxide from a carbonate, as any acid does.

All 14 Reactivity of Carboxylic Acids MCQs → Reactivity of Carboxylic Acids notes →

Conversion of Carboxylic Acids

7.Acetic anhydride is a product of acetic acid as a result of which reaction? (MDCAT 2020)

  1. dehydration
  2. reduction
  3. oxidation
  4. esterification
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Correct answer: (a) dehydration

Two molecules of the acid lose one molecule of water between them.

8.Acetic acid is mixed with thionyl chloride. Which product is obtained? (MDCAT 2023)

  1. $\mathrm{CH_3COCl+SO_2+HCl}$
  2. $\mathrm{CH_3Cl+CH_3COCl}$
  3. $\mathrm{CH_3COOH+SO_2}$
  4. $\mathrm{CH_3CHO+HCl}$
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Correct answer: (a) $\mathrm{CH_3COCl+SO_2+HCl}$

Thionyl chloride replaces the $-\mathrm{OH}$ of the acid by chlorine, and the by-products are gases.

9.When carboxylic acids are heated with an alcohol in the presence of sulphuric acid, one of the following is formed: (MDCAT 2024)

  1. amides
  2. acyl chlorides
  3. esters
  4. acid anhydrides
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Correct answer: (c) esters

That is esterification, with the sulphuric acid as catalyst and water as the other product.

All 23 Conversion of Carboxylic Acids MCQs → Conversion of Carboxylic Acids notes →

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