Conversion of Carboxylic Acids

Conversion of Carboxylic Acids MDCAT MCQs with answers

23 past paper MCQs on Conversion of Carboxylic Acids, from the Carboxylic Acids unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

Read the notes first Practise the unit as a quiz

1.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.

2.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.

3.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.

4.Fischer ESTERIFICATION Is which type of reaction: (UHS MDCAT 2025)

  1. Condensation
  2. Substitution
  3. Elimination
  4. Dehydrogenation
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Correct answer: (a) Condensation

An acid and an alcohol join with the loss of water, which makes esterification a condensation.

5.Carboxylic acid reacts with ammonia to form ammonium salts which on heating produces: (UHS MDCAT 2025)

  1. Carbonates
  2. Alkane
  3. Ester
  4. Amide
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Correct answer: (d) Amide

The ammonium salt loses water on strong heating and leaves the amide.

6.Which of the following compound will react with 2,2-dimethyl propanoic acid to produce ester? (NUMS MDCAT 2025)

  1. Ethanoic acid
  2. Propane
  3. Ethanol
  4. Propanone
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Correct answer: (c) Ethanol

An ester is an acid plus an alcohol, so ethanol is the reagent that gives one.

7.Formic acid reacts with ethanol in presence of acid catalyst produces: (SIBA MDCAT 2025)

  1. Ester
  2. Ether
  3. Acid anhydride
  4. Phenol
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Correct answer: (a) Ester

An acid and an alcohol with an acid catalyst give an ester and water.

8.Reduction of carboxylic acid by using lithium aluminiumhydride produce (SZABMU MDCAT 2025)

  1. Alcohol
  2. acid halide
  3. ester
  4. alkane
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Correct answer: (a) Alcohol

Lithium aluminium hydride reduces the carboxyl group all the way to a primary alcohol.

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

  1. Amides
  2. Acyl chloride
  3. Esters
  4. Acid Anhydride
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Correct answer: (c) Esters

An acid and an alcohol with a little sulphuric acid give an ester and water.

10.Carboxylic acid reacts with Alcohol to form: (SZABMU MDCAT 2023)

  1. Ester
  2. Aldehyde
  3. Ketone
  4. Alkyl Halide
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Correct answer: (a) Ester

An acid and an alcohol give an ester and water.

11.Which of the following reacts with Carboxylic Acid to form Ester? (NUMS MDCAT 2023)

  1. Aldehyde
  2. Alkyl Halide
  3. Ketones
  4. Alcohol
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Correct answer: (d) Alcohol

An acid and an alcohol give an ester and water.

12.Mr. Khan mix acetic acid with thionyl chloride. Which product is obtained? (UHS MDCAT 2023)

  1. CH3COCI + SO2 + HCl
  2. CH3CI + CH3COCI
  3. CH3COOCH3 + SO2
  4. CH3CI +SO2+HCI
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Correct answer: (a) CH3COCI + SO2 + HCl

Thionyl chloride replaces the hydroxyl group with chlorine and leaves gaseous by-products.

13.The flavour of amyl butyrate is: (PMC MDCAT 2022)

  1. Mango
  2. Raspberry
  3. Apricot
  4. Orange
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Correct answer: (c) Apricot

Amyl butyrate smells of apricots; the esters are what give fruits their scent.

14.Complete the following reaction: CH3COOC2H5 +H2O —–> (PMC MDCAT 2022)

  1. Both HOC2H5 and CH3CO2H
  2. Both HOCH3 and CH3CO3H
  3. HOC3H6 Only
  4. CH3CO2H Only
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Correct answer: (a) Both HOC2H5 and CH3CO2H

Hydrolysing the ester gives back the alcohol and the acid.

15.Hydrolysis of acyl chloride results in the formation of: (PMC MDCAT 2020)

  1. Acid anhydride
  2. Carboxylic acid
  3. Amides
  4. Esters
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Correct answer: (b) Carboxylic acid

Water attacks the acyl chloride and leaves the carboxylic acid and hydrogen chloride.

16.Carboxylic acids can be reduced to corresponding alcohols. Which of the following reagent can be used for this purpose? (UHS MDCAT 2019)

  1. KMnO4
  2. LiAlH4
  3. K2Cr2O4
  4. H2SO4
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Correct answer: (b) LiAlH4

Lithium aluminium hydride reduces the carboxyl group all the way to a primary alcohol.

17.Which of the following reagent is required for preparation of acyl chloride (CH3COCl) from ethanoic aicd? (UHS MDCAT 2019)

  1. PCl5
  2. POCl3
  3. CH3Cl
  4. HCl
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Correct answer: (a) PCl5

Phosphorus pentachloride replaces the hydroxyl group of the acid with chlorine.

18.Which balanced chemical equation show the formation of ethanoyl chloride using thionyl chloride? (UHS MDCAT 2019)

  1. HCOOH + SOCl2 —> HCOCI + SO2 + HCI
  2. CH3CH2COOH + 2SOCl -> CH3CH2COCl + SO2 + HCI
  3. CH3CH2COOH + 2SOCl -> CH3CH2COC1 + SO3 + HCI
  4. CH3COOH + SOCl2 -> CH3COCl + SO2 + HCI
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Correct answer: (d) CH3COOH + SOCl2 -> CH3COCl + SO2 + HCI

Ethanoic acid with thionyl chloride gives ethanoyl chloride, sulphur dioxide and hydrogen chloride.

19.Which product is formed by the reaction of carboxylic acid with alcohol? (UHS MDCAT 2018)

  1. Alkane
  2. Ether
  3. Aldehyde
  4. Ester
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Correct answer: (d) Ester

An acid and an alcohol give an ester and water.

20.Which one of the following compounds act as a catalyst when alcohols react with carboxylic acids. (UHS MDCAT 2018)

  1. Pt
  2. Conc. HNO3
  3. Ni
  4. Conc. H2SO4
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Correct answer: (d) Conc. H2SO4

Concentrated sulphuric acid catalyses the esterification and takes up the water.

21.Catalytic oxidation of alkanes results in the formation of _____: (UHS MDCAT 2017)

  1. Carboxylic acid
  2. Aldehyde
  3. Ketone
  4. Alcohol
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Correct answer: (d) Alcohol

Controlled catalytic oxidation stops at the alcohol.

22.During esterification, the bond from alcohol that breaks in between: (UHS MDCAT 2017)

  1. Carbon and oxygen
  2. Oxygen and hydrogen
  3. Carbon and carbon
  4. None of the given options
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Correct answer: (b) Oxygen and hydrogen

Isotopic labelling shows the alcohol loses its hydrogen and keeps its oxygen in the ester.

23.Which one of the following reaction of carboxylic acid is reversible? (UHS MDCAT 2016)

  1. Esterification
  2. Salt formation
  3. Reaction with PCl5
  4. Reaction with SOCl2
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Correct answer: (a) Esterification

Esterification is an equilibrium, which is why the water is removed to drive it forward.

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