What is the percentage by mass of carbon in ethanoic acid, CH₃COOH (C = 12, H = 1, O = 16)?
Correct answer A. 40%
Topic / 36 questions
Carboxylic Acids MCQs
Carboxylic Acids MCQs are multiple-choice questions on the naming, structure, preparation and reactions of carboxylic acids and their conversion into acyl chlorides, anhydrides, esters and amides. They follow the MDCAT chemistry curriculum, and every question on MCQs360 shows its correct answer instantly so you can revise reagents and products with quick feedback.
- Gases 40
- Liquids 40
- Solids 40
- Chemical Equilibrium 40
- Reaction Kinetics 40
- Thermochemistry and Energetics 40
- Electrochemistry 40
- Fundamental Concepts of Chemistry 40
- Atomic Structure 39
- Chemical Bonding 39
- Alcohols and Phenols 38
- Industrial Chemistry 37
- Aldehydes and Ketones 37
- Alkyl Halides 37
- s- and p-Block Elements 37
- Chemistry of Hydrocarbons 36
- Fundamental Principles of Organic Chemistry 36
- Carboxylic Acids 36
- Transition Elements 35
- Macromolecules 35
Methylmagnesium bromide reacts with carbon dioxide, and the product is hydrolysed with dilute acid. What is formed?
Correct answer A. Ethanoic acid
Which reagent liberates CO₂ with ethanoic acid but not with phenol?
Correct answer C. Sodium hydrogencarbonate solution
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Which reagent converts ethanoic acid into ethanoyl chloride?
Correct answer C. Thionyl chloride, SOCl₂
Heating ethanoic acid with phosphorus pentoxide (P₂O₅) forms ____.
Correct answer C. ethanoic anhydride
Reduction of ethanoic acid with LiAlH₄ gives ____.
Correct answer B. ethanol
Carboxylic acids have unusually high boiling points mainly because they ____.
Correct answer B. form hydrogen-bonded dimers
Alkaline hydrolysis of an ester to form a carboxylate salt and an alcohol is called ____.
Correct answer D. saponification
What volume of CO₂ at STP is evolved when 6.0 g of ethanoic acid reacts with excess sodium hydrogencarbonate (CH₃COOH = 60)?
Correct answer C. 2.24 dm³
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What volume of 0.1 mol dm⁻³ NaOH is needed to neutralise 0.45 g of anhydrous ethanedioic acid, (COOH)₂ (M = 90 g mol⁻¹)?
Correct answer C. 100 cm³
Hydrolysis of ethanenitrile (CH₃CN) by boiling with dilute acid gives ____.
Correct answer D. ethanoic acid
Which products form when ethyl ethanoate is heated under reflux with aqueous NaOH?
Correct answer C. Sodium ethanoate and ethanol
Take C = 12, H = 1, O = 16. What is the percentage by mass of oxygen in ethanoic acid, CH₃COOH?
Correct answer A. 53.3%
What mass of ethanoyl chloride (M = 78.5 g/mol) is formed from 0.25 mol of ethanoic acid with excess SOCl₂?
Correct answer A. 19.6 g
12.0 g of ethanoic acid (M = 60 g/mol) reacts with excess ethanol to give 11.0 g of ethyl ethanoate (M = 88 g/mol). What is the percentage yield?
Correct answer C. 62.5%
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What volume of 0.10 mol/dm³ NaOH exactly neutralises 0.30 g of ethanoic acid (M = 60 g/mol)?
Correct answer C. 50 cm³
Take CO₂ = 44 g/mol. What mass of CO₂ is produced when 6.0 g of ethanoic acid (M = 60 g/mol) reacts with excess NaHCO₃?
Correct answer D. 4.4 g
Heating sodium ethanoate with soda lime gives ____.
Correct answer D. Methane
What is observed when ethanoyl chloride is added to water?
Correct answer A. Steamy fumes of HCl form and ethanoic acid is produced
What is observed when ethanoic acid is added to aqueous sodium hydrogencarbonate?
Correct answer A. Effervescence of carbon dioxide
About Carboxylic Acids MCQs
Questions in this topic begin with IUPAC names such as propanoic acid and 2-methylpropanoic acid, the structure of the carboxyl group and preparation by oxidation or hydrolysis of nitriles. Acidity questions compare carboxylic acids with phenols and alcohols and include pH calculations for ethanoic acid from its Ka value. Reaction questions cover reduction with lithium aluminium hydride, decarboxylation of sodium ethanoate with soda lime, the formation of amides by heating ammonium salts and the conversion of acids into acyl chlorides, anhydrides and esters. You will also meet the hydrolysis of ethanoyl chloride and the alkaline hydrolysis of esters.
Key facts to remember
- Carboxylic acids contain the –COOH group and are named with the suffix -oic acid, for example CH₃CH₂COOH is propanoic acid.
- Ethanoic acid is a weak acid with Ka = 1.8 × 10⁻⁵ mol dm⁻³ (pKa 4.74); its anion is stabilised by resonance.
- Carboxylic acids liberate CO₂ from sodium hydrogencarbonate, which distinguishes them from phenols.
- SOCl₂, PCl₅ or PCl₃ convert a carboxylic acid into an acyl chloride, and heating with an alcohol and concentrated H₂SO₄ gives an ester.
- Lithium aluminium hydride, LiAlH₄, reduces carboxylic acids to primary alcohols.
- Heating sodium ethanoate with soda lime removes CO₂ and gives methane.
Exams that include Carboxylic Acids MCQs
Pakistan
- MDCAT
- ECAT
- NUMS
- AKU
- FSc boards
India
- NEET
- JEE Main
Bangladesh
- HSC
- Medical Admission Test
How to prepare for Carboxylic Acids MCQs
- Draw a conversion map linking the acid to its acyl chloride, anhydride, ester and amide with the reagents on each arrow.
- Use pH = ½(pKa − log c) for quick weak acid pH calculations.
- Learn the reactivity order of acid derivatives: acyl chloride > anhydride > ester > amide.
- Remember that alkaline ester hydrolysis gives the carboxylate salt and an alcohol, not the free acid.
Frequently asked questions
What does the MDCAT syllabus include in Carboxylic Acids?
The PMDC MDCAT curriculum covers the nomenclature, structure and preparation of carboxylic acids, their reactivity and their conversion to acyl halides, anhydrides and esters, along with interconversions between these derivatives.
Which exams ask Carboxylic Acids MCQs?
Carboxylic acid questions appear in MDCAT, ECAT, NUMS and AKU entry tests and FSc board papers in Pakistan, in NEET and JEE Main in India, and in HSC and medical admission tests in Bangladesh.
Why are carboxylic acids stronger acids than alcohols?
When a carboxylic acid loses a proton, the negative charge on the carboxylate ion is shared equally between two oxygen atoms by resonance. The alkoxide ion from an alcohol has no such stabilisation, so carboxylic acids ionise more readily.
Last reviewed October 2026