Carboxylic Acid MCQs with Answers
Which of the following functional groups defines a carboxylic acid?
The carboxyl group is a combination of which two groups?
Carbonyl and ether
Carbonyl and hydroxyl
Hydroxyl and aldehyde
Carbonyl and alkyl
What is the IUPAC name for formic acid?
Ethanoic acid
Propanoic acid
Methanoic acid
Butanoic acid
Acetic acid was first isolated from which source?
Ants
Butter
Vinegar
Fats and oils
What is the common name for CH₃CH₂CH₂COOH?
Acetic acid
Propionic acid
Butyric acid
Valeric acid
Which of the following is an example of an aliphatic dicarboxylic acid?
Benzoic acid
Acetic acid
Oxalic acid
Formic acid
How many carboxyl groups are present in a tricarboxylic acid?
The IUPAC names of saturated monocarboxylic acids are derived from alkanes by changing the ending 'e' to:
Which of the following is the general formula for an aliphatic carboxylic acid?
Ar-C-OH
R-C-OH (where R = H or an alkyl group)
R-CHO
R-OH
What type of carboxylic acid is benzoic acid?
Aliphatic monocarboxylic acid
Aliphatic dicarboxylic acid
Aromatic monocarboxylic acid
Aromatic dicarboxylic acid
Primary alcohols and aldehydes can be oxidized to carboxylic acids using which of the following reagents?
LiAlH₄ in an acidic medium
K₂Cr₂O₇ in an acidic medium
NaBH₄ in an acidic medium
H₂/Ni in an acidic medium
The hydrolysis of alkanenitriles to carboxylic acids requires boiling with:
Strong bases only
Mineral acids or alkalis
Water only
Organic solvents
How many carbon atoms does the carboxylic acid produced from an alkyl halide via alkanenitrile hydrolysis have, compared to the original alkyl halide?
One less carbon atom
The same number of carbon atoms
One carbon atom more
Two carbon atoms more
Carboxylic acids can be prepared from Grignard reagents by reacting them with:
Water
Carbon dioxide
Alcohols
Aldehydes
In the preparation of carboxylic acids from Grignard reagents, the addition product is reacted with:
An alkali
A mineral acid
An organic base
An alcohol
The hydrolysis of esters to form carboxylic acids is typically done by boiling with:
Dilute HCl
Conc. sodium hydroxide
Aqueous ethanol
Acetic acid
Symmetrical alkenes when heated with alkaline KMnO₄ are cleaved at the double bond to form:
Alcohols
Ketones
Carboxylic acids
Ethers
What is the smell characteristic of the first three aliphatic acids (formic, acetic, propionic acid)?
Pleasant and fruity
Pungent
Odorless
Sweet
Why are the first four members of aliphatic acids very soluble in water?
Due to van der Waals forces
Due to hydrogen bonding
Due to ionic character
Due to their small size only
Carboxylic acids have relatively high boiling points due to:
Strong dipole-dipole interactions
Intermolecular hydrogen bonding
London dispersion forces
Covalent bonding
In non-polar solvents like benzene, carboxylic acids exist as:
Monomers
Cyclic dimers
Polymers
Open-chain trimers
What is the melting point trend observed for carboxylic acids with an even number of carbon atoms compared to their odd-numbered counterparts?
They have lower melting points.
They have higher melting points.
Their melting points are similar.
There is no observable trend.
Which of the following is a laboratory method for preparing acetic acid?
Oxidation of methane
Oxidation of ethyl alcohol
Reduction of methyl cyanide
Fermentation of glucose directly
The hydrolysis of ethanenitrile to acetic acid proceeds through which intermediate?
Ethyl acetate
Acetamide
Acetaldehyde
Acetic anhydride
What is 'glacial acetic acid' characterized by?
Its very low boiling point.
Its strong pungent smell.
Its ability to freeze into an ice-like solid at 17 °C.
Its immiscibility with water.
Which of the following statements about the carboxyl group's reactivity is true?
It only displays the chemistry of the carbonyl group.
It only displays the chemistry of the hydroxyl group.
It displays the chemistry of both the carbonyl and the hydroxyl groups.
It has no specific reactivity due to its stable nature.
In most reactions of carboxylic acids, which part of the molecule is typically retained?
The hydroxyl group
The carbonyl group
The carboxyl group
The alkyl group
The reactivity of carboxylic acid molecules is primarily a consequence of the presence of which group?
Hydroxyl group
Alkyl group
Carbonyl group
Carboxyl group as a whole
Carboxylic acids are considered weaker acids compared to:
Phenols
Alcohols
Mineral acids
Water
When dissolved in water, carboxylic acids furnish which ion?
What is formed when carboxylic acids react with bases like NaOH or KOH?
Esters
Ethers
Salts
Aldehydes
Which gas is evolved when carboxylic acids decompose carbonates and bicarbonates?
Hydrogen gas
Oxygen gas
Carbon dioxide gas
Methane gas
The reaction of acetic acid with sodium carbonate produces sodium acetate, water, and:
Methane
Carbon monoxide
Carbon dioxide
Hydrogen
When carboxylic acids react with active metals (Na, K, Ca, Mg), what is evolved along with the formation of their salts?
Oxygen gas
Hydrogen gas
Nitrogen gas
Carbon dioxide gas
The -OH group of carboxylic acids can be replaced by which of the following to form acid derivatives?
H and CH₃
X, OR and NH₂
O and N
Only halogen atoms
What type of reaction occurs when a nucleophile attacks the carboxyl group, followed by the displacement of the -OH group?
Addition reaction
Elimination reaction
Nucleophilic addition followed by substitution
Oxidation reaction
The reaction of CH₃COOH with PCl₅ produces CH₃COCl, POCl₃, and:
Heating carboxylic acids with alcohols in the presence of concentrated H₂SO₄ leads to the formation of:
Ethers
Aldehydes
Esters
Ketones
What is the characteristic smell of esters, often leading to their use as artificial flavors?
Pungent
Unpleasant
Fruity
Sour
What are ammonium salts formed when carboxylic acids react with ammonia?
Esters
Acid anhydrides
Acid amides
Carboxylic acids
Which reagent is used to dehydrate carboxylic acids on strong heating to form acid anhydrides?
Concentrated H₂SO₄
Phosphorus pentoxide (P₂O₅)
Lithium aluminum hydride (LiAlH₄)
Potassium permanganate (KMnO₄)
What is the product of the partial reduction of carboxylic acids with lithium aluminum hydride (LiAlH₄)?
Alkanes
Aldehydes
Alcohols
Ethers
What are carboxylic acids completely reduced to when reacted with HI and red phosphorus?
Alkenes
Alkynes
Alkanes
Aldehydes
Which of the following is true regarding the reactivity of carboxylic acids based on the carbonyl group?
The carbonyl group decreases the reactivity.
The carbonyl group has no influence on reactivity.
The reactivity is a consequence of the presence of the carbonyl group.
The carbonyl group only affects physical properties, not reactivity.
When CH₃COOH reacts with SOCl₂, what are the products?
CH₃COCl + H₂O
CH₃COCl + SO₂ + HCl
CH₃COCl + SO₃ + HCl
CH₃COOS + H₂O
What happens to the proton (H⁺) in the presence of water (H₂O) when a carboxylic acid dissociates?
It remains as H⁺
It breaks away as H₃O⁺ ion
It forms a covalent bond with the carboxylate ion
It combines with the solvent to form an insoluble precipitate
What type of functional group is formed when the -OH group of a carboxylic acid is replaced by −NH₂?
Ester
Acyl halide
Amide
Anhydride
Which of the following is a key step in the mechanism of ester formation from carboxylic acids and alcohols?
Deprotonation of the carboxylic acid
Elimination of an alkane
Protonation of the carboxylic acid
Formation of a ketone intermediate
What is the product when ammonium acetate (CH₃COONH₄) is heated?
Acetic acid + Ammonia
Acetic anhydride + Water
Acetamide + Water
Ethyl acetate + Water
The overall process by which carboxylic acids react with alcohols to form esters and water is known as:
Saponification
Hydrolysis
Esterification
Dehydration
What happens to the -OH group of a carboxylic acid when it forms a derivative like an acyl halide, ester, or amide?
It is reduced to a hydrogen atom.
It is oxidized to a carbonyl group.
It is replaced by another group.
It remains unchanged.
Which of the following is NOT a common carboxylic acid derivative discussed in the text?
Acyl halides
Ethers
Esters
Amides
What is the product when acetic acid (CH₃COOH) reacts with PCl₅?
Acetyl chloride (CH₃COCl)
Acetic anhydride
Ethyl acetate
Acetamide
Which reagent is used to convert carboxylic acids into acyl chlorides, along with SO₂ and HCl as by-products?
The formation of an ester from a carboxylic acid and an alcohol in the presence of concentrated H₂SO₄ is known as:
Saponification
Hydrolysis
Esterification
Amidation
Which of the following compounds has a fruity smell and is used as an artificial flavor?
Carboxylic acid
Aldehyde
Ester
Amide
What is the product formed when carboxylic acids react with NH₃ and are subsequently heated?
Ammonium salt only
Acid anhydride
Acid amide
Alkyl nitrile
The dehydration of carboxylic acids using phosphorus pentoxide (P₂O₅) on strong heating leads to the formation of:
Esters
Acid amides
Acid anhydrides
Acyl halides
Which of the following is a common step in the mechanism of forming acyl chlorides from carboxylic acids using SOCl₂?
Addition of water
Formation of a sulfinyl chloride intermediate
Reduction of the carbonyl group
Protonation of the alkyl group
What is the product of the reaction between ethanoic acid (CH₃COOH) and ethanol (C₂H₅OH) in the presence of H₂SO₄?
Ethyl alcohol
Ethanoic anhydride
Ethyl acetate
Acetamide
The conversion of a carboxylic acid into an acyl halide involves the replacement of the -OH group by a:
Hydrogen atom
Halogen atom
Alkoxy group
Amine group
The reaction of CH₃COOH with NH₃ initially forms an ammonium salt (CH₃COONH₄). This is an example of a reaction involving:
The -OH group of the carboxylic acid
The complete carboxyl group
The hydrogen atom of the carboxyl group
Oxidation of the acid
What is the name of the derivative formed when the -OH group of a carboxylic acid is replaced by an -OR group?
Amide
Acyl halide
Ester
Acid anhydride
Which reagent is used to convert acyl chlorides to carboxylic acids?
What is the product when an acid anhydride reacts with an alcohol?
Acyl halide
Ester
Amide
Carboxylic acid only
How can an ester be converted back to its parent carboxylic acid?
By reduction with LiAlH₄
By heating with P₂O₅
By saponification
By reaction with SOCl₂
What is the product when an amide is hydrolyzed in the presence of an acid or a base?
An ester
An acyl halide
A carboxylic acid
An acid anhydride
Which of the following reactions is an example of an interconversion between carboxylic acid derivatives?
Carboxylic acid + Alcohol → Ester
Amide + Water → Carboxylic acid
Acyl halide + Water → Carboxylic acid
All of the above
The reaction of an acyl chloride with an alcohol yields:
An acid anhydride
An amide
An ester
A carboxylic acid
What product is formed when an acyl chloride reacts with ammonia?
An ester
An acid anhydride
An amide
A carboxylic acid
Which derivative can be used to synthesize an amide from a carboxylic acid without going through the ammonium salt intermediate?
Ester
Acid anhydride
Acyl halide
None of the above
The reaction of an acid anhydride with an amine produces:
An ester and water
A carboxylic acid
An acyl halide
An alcohol
Which of the following reagents is most suitable for the reduction of an ester to an alcohol?
What is the primary characteristic that makes acyl halides highly reactive among carboxylic acid derivatives?
The bulky halogen atom
The strong carbon-halogen bond
The good leaving group ability of the halide ion
The presence of a hydrogen bond
The conversion of an acid anhydride to a carboxylic acid can be achieved by:
Reaction with an alcohol
Reaction with an amine
Reaction with water
Reduction with LiAlH₄
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