Chemistry — AS

Aldehydes & Ketones — Multiple-Choice Questions (Cambridge International AS Chemistry): Exam Questions

Exam code:9701

21 questions · 21 marks · ≈ 21 min

Guided practice

11 markeasy

What is formed when butanone is warmed with a solution of NaBH₄?

Choose your answer

Butan-1-ol

Butan-2-ol

Butanal

Butane

21 markeasy

In 1903, Arthur Lapworth investigated the reaction of hydrogen cyanide with propanone.

What is the name of this type of mechanism?

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Electrophilic addition

Electrophilic substitution

Nucleophilic addition

Nucleophilic substitution

31 markeasy

Which carbonyl compound(s) react with both LiAlH₄ and Tollens’ reagent?

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Aldehydes only

Both aldehydes and ketones

Ketones only

Neither aldehydes nor ketones

41 markeasy

An aqueous methanolic solution of NaBH₄ acts as a reducing agent when added to propanal, CH₃CH₂CHO.

What is the first step of this mechanism?

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Attack of an H^– ion at the carbon atom of the carbonyl group.

Attack of an H^– ion at the oxygen atom of the carbonyl group.

Attack of an H⁺ ion at the carbon atom of the carbonyl group.

Attack of an H⁺ ion at the oxygen atom of the carbonyl group.

51 markeasy

The characteristic smell of burnt sugar is partly caused by the following compound.

Structure of a compound containing both an aldehyde and a ketone functional group, contributing to the smell of burnt sugar

Which reagent will react with both functional groups?

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Acidified potassium dichromate (VI)

Fehling’s solution

Hydrogen cyanide

Sodium hydroxide

61 markeasy

In which reaction is the organic compound oxidised?

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CH₃CH₂CH₂OH + concentrated H₃PO₄

CH₃CH₂CHO + Tollens’ reagent

CH₃CH₂CN + dilute H₂SO₄

CH₃COCH₂CH₃ + 2,4-dinitrophenylhydrazine reagent

71 markeasy

Ethanal, CH₃CHO, is reduced using NaBH₄ in aqueous ethanol.

What is the first step of this mechanism?

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The carbon atom of the carbonyl group is attacked by an H^– ion

The carbon atom of the carbonyl group is attacked by an H⁺ ion

The oxygen atom of the carbonyl group is attacked by an H^– ion

The oxygen atom of the carbonyl group is attacked by an H⁺ ion

81 markeasy

The orange colour of carrots is due to the presence of β-carotene, the structure of which is shown in the diagram below.

Structure of β-carotene showing a long conjugated carbon chain with multiple C=C double bonds and two six-membered rings with methyl substituents at each end

Excess hot concentrated acidified potassium manganate(VII) will oxidise β-carotene.

When an individual molecule of β-carotene is oxidised in this way there are multiple possible products.

How many of these product molecules contain a ketone functional group?

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91 markeasy

Hex-3-enal is used as a flavouring agent.

CH₃CH₂CH=CHCH₂CHO

Which row correctly shows the product formed when hex-3-enal is treated with the given reducing agent?

	Product	Reducing agent
A	CH₃(CH₂)₄CH₃	H₂ + Ni
B	CH₃(CH₂)₄CH₂OH	NaBH₄
C	CH₃(CH₂)₄CHO	H₂ + Ni
D	CH₃(CH₂)₄CHO	NaBH₄

Choose your answer

101 markmedium

When alkaline I₂ solution is added to butanone, a yellow precipitate is formed.

Which of the following compounds is responsible for the precipitate?

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CH₃CH₂CO₂^-

CH₃CH₂COCH₂I

CH₃CHICOCH₃

CHI₃

111 markmedium

The colour of warm acidified potassium dichromate(VI) changes from orange to green when added to compound Y. 1 mol of Y reacts with 2 mol of hydrogen cyanide in the presence of potassium cyanide.

What could Y be?

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CH₃CH₂CH₂CHO

CH₃COCH₂COCH₃

H₂C=CHCH₂CHO

OHCCH₂CH₂CHO

121 markmedium

Hydroxyethanal has the structural formula HOCH₂CHO.

In an experiment hydroxyethanal is heated under reflux with an excess of acidified potassium dichromate (VI) until no further oxidation takes place.

What is the skeletal formula of the organic product formed in the experiment?

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131 markmedium

Which reagent will give similar results with both propanone and propanal?

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2,4-dinitrophenylhydrazine reagent

Acidified aqueous potassium dichromate (VI)

Fehling’s solution

Tollens’ reagent

141 markmedium

Carvone is used as a flavouring for spearmint chewing gum.

Structure of carvone, a six-membered ring compound with a ketone group, an isopropenyl substituent, and a methyl group

When carvone is heated under reflux with excess hot concentrated acidified potassium manganate(VII) the products carbon dioxide and compound X are formed.

X contains nine carbon atoms and reacts with 2,4-dinitrophenylhydrazine reagent.

What is the maximum number of molecules of 2,4-dinitrophenylhydrazine that will react with one molecule of X?

Choose your answer

151 markmedium

When compounds 1, 2 and 3 react with PCl₅, hydrogen chloride is evolved. However, only one of the three reacts with 2,4-dinitrophenylhydrazine reagent.

Which one of the following combinations could be 1, 2 and 3?

Table showing four combinations (A–D) of three organic compounds with their structural formulae. Each row presents a different set of compounds labelled 1, 2 and 3 for students to evaluate against the criteria given

Choose your answer

161 markmedium

An organic liquid X gives the following results:

Forms an orange precipitate with 2,4-DNPH
Does not form a silver mirror with Tollens’ reagent
Forms a yellow precipitate with alkaline aqueous iodine

What is the identity of X?

Choose your answer

Butan-2-ol

Butanone

Pentan-3-one

Propanal

171 markmedium

An organic compound X has a molecular ion peak at m/z = 58 in its mass spectrum.

Experimental data for compound X is shown in the table below:

Test	Observation
Addition of 2,4-dinitrophenylhydrazine (2,4-DNPH)	Orange precipitate formed
Warming with Tollens' reagent	No visible change

What is the identity of compound X?

Choose your answer

CH₃CH₂CH₂CH₃

CH₃CH₂CHO

CH₃CH₂COOH

CH₃COCH₃

181 markhard

When HCN reacts with butanal, CH₃CH₂CH₂CHO, product X is formed. If X is then hydrolysed by aqueous acid, product Y is produced.

When pentanal, CH₃CH₂CH₂CH₂CHO, is heated under reflux with acidified potassium dichromate(VI), product Z is formed.

What is the difference in relative molecular mass of products Y and Z?

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191 markhard

Hydroxynitriles can be made from carbonyl compounds by generating CN^– ions from HCN in the presence of a weak base.

Reaction scheme showing nucleophilic addition of CN^–^ to a carbonyl compound (C=O) to give a hydroxynitrile product with an OH group and a CN group on the same carbon

In a similar reaction, ^–CH₂CO₂CH₃ ions are generated from CH₃CO₂CH₃ by strong bases.

Which compound can be made from an aldehyde and CH₃CO₂CH₃ in the presence of a strong base?

Choose your answer

(CH₃)₂C(OH)CH₂CO₂CH₃

CH₃CH(OH)CO₂CH₃

CH₃CH₂CH(OH)CH₂CO₂CH₃

CH₃CO₂CH₂CH(OH)CH₃

201 markhard

When compound T reacts with its own oxidation product, a sweet-smelling liquid is produced.

What is the identity of compound T?

Choose your answer

Butan–1–ol

Butanal

Butanoic acid

Butanone

211 markhard

1 mol of CH₃COCH₂CH₂CHO is placed into each of three separate test-tubes.

An excess of NaBH₄ is added to test-tube 1 and an excess of acidified potassium manganate(VII) is added to test-tube 2. No reagent is added to test-tube 3.

An excess of HCN is then added to each test-tube.

Which row correctly shows the number of moles of HCN that react with the organic compound in each test-tube?

	test-tube 1	test-tube 2	test-tube 3
A	0	1	2
B	0	2	2
C	1	1	2
D	2	1	0

Choose your answer

Product

Reducing agent

CH₃(CH₂)₄CH₃

H₂ + Ni

CH₃(CH₂)₄CH₂OH

NaBH₄

CH₃(CH₂)₄CHO

H₂ + Ni

CH₃(CH₂)₄CHO

NaBH₄

Test

Observation

Addition of 2,4-dinitrophenylhydrazine (2,4-DNPH)

Orange precipitate formed

Warming with Tollens' reagent

No visible change

test-tube 1

test-tube 2

test-tube 3