Most Important Aldehydes And Ketones Quiz Test Online

Aldehydes And Ketones Quiz Test Online

Aldehydes and Ketones Test. 1

1 / 20

1) For the industrial preparation of formaldehyde, methanol vapours and air are passed over which catalyst at 500 °C?

Platinum

Iron oxide-molybdenum oxide

Copper

Zinc amalgam

Formaldehyde is manufactured by passing a mixture of methanol vapours and air over iron oxide-molybdenum oxide or silver catalyst at 500 °C.

2 / 20

2) Aldehydes are generally obtained by the oxidation of which type of alcohols?

Tertiary alcohols

Phenols

Secondary alcohols

Primary alcohols

Aldehydes are obtained by the oxidation of primary alcohols.

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3) Which of the following aldehydes would have "Propionaldehyde" as its common name?

CH₃-C(=O)-H

H-C(=O)-H

CH₃-CH₂-C(=O)-H

CH₃-CH₂-CH₂-C(=O)-H

Propionic acid has three carbons, so its corresponding aldehyde is CH₃-CH₂-C(=O)-H, which is called Propionaldehyde.

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4) In the laboratory preparation of acetaldehyde, ethyl alcohol is oxidized using:

Neutral KMnO₄ solution

Acidified sodium dichromate solution

Hydrogen peroxide

Basic K₂Cr₂O₇ solution

Acetaldehyde is prepared in the laboratory by the oxidation of ethyl alcohol with acidified sodium dichromate solution.

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5) Ketones are generally prepared by the oxidation of which type of alcohols?

Secondary alcohols

Tertiary alcohols

Enols

Primary alcohols

Ketones are prepared by the oxidation of secondary alcohols.

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6) Formalin is a mixture containing 40% formaldehyde, 8% methyl alcohol, and what percentage of water?

60%

40%

52%

25%

Formalin is a mixture of 40% formaldehyde, 8% methyl alcohol and 52% water.

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7) What is the common name for CH₃-C(=O)-CH₃?

Ethyl methyl ketone

Diethyl ketone

Propanone

Acetone

CH₃-C(=O)-CH₃ is commonly known as Acetone. It is also called Dimethyl ketone.

8 / 20

8) Why is acetaldehyde distilled off immediately during its laboratory preparation from ethyl alcohol oxidation?

To increase the yield

To separate it from unreacted ethyl alcohol

To prevent its polymerization

To prevent its further oxidation to acetic acid

The acetaldehyde formed in liquid state is immediately distilled off during its preparation to prevent its oxidation to acetic acid.

9 / 20

9) Acetaldehyde can also be prepared by the dry distillation of a mixture of calcium salts of which two acids?

Butyric acid and formic acid

Formic acid and acetic acid

Oxalic acid and malonic acid

Acetic acid and propanoic acid

Acetaldehyde can also be prepared by the dry distillation of a mixture of calcium salts of formic acid and acetic acid.

10 / 20

10) What is the general formula for a ketone?

R-CHO

R-COOH

R-O-R'

R-C(=O)-R'

A ketone may be represented by the general formula R-C(=O)-R', where the carbonyl group is bonded to two carbon atoms within a chain.

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11) In the common naming of aldehydes, Greek letters are used to indicate the positions of other groups. Which letter indicates the carbon atom adjacent to the carbonyl group?

The carbon adjacent to the carbonyl group is designated as the α-carbon in common naming.

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12) Industrially, acetaldehyde is prepared by the air oxidation of ethylene using which catalyst system?

FeO₃/Mo₂O₃

Palladium chloride catalyst

Raney Nickel

Ni/Al₂O₃

Acetaldehyde is prepared industrially by air oxidation of ethylene using palladium chloride catalyst with a cupric chloride promoter.

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13) The common name for H-C(=O)-H is:

Acetaldehyde

Formaldehyde

Propanal

Butyraldehyde

H-C(=O)-H is commonly known as Formaldehyde.

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14) What is the IUPAC name for CH₃-CH₂-C(=O)-CH₃?

Acetone

Butanone

2-Propanone

Ethyl methyl ketone

CH₃-CH₂-C(=O)-CH₃ is a four-carbon compound with a ketone at the second carbon, so its IUPAC name is Butanone (or 2-Butanone).

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15) What is the IUPAC name for CH₃-C(=O)-H?

Propanal

Ethanal

Methanal

Butanone

The IUPAC name for CH₃-C(=O)-H is Ethanal. IUPAC names of aldehydes are derived from alkanes by replacing the 'e' with 'al'.

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16) Besides the oxidation of secondary alcohols, ketones can also be prepared by the:

Hydration of alkynes

Dehydration of primary alcohols

Reduction of carboxylic acids

Hydration of alkanes

Ketones are also prepared by hydration of alkynes.

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17) In an aldehyde, the carbonyl group is bonded to at least one:

Oxygen atom

Carbon atom

Hydrogen atom

Alkyl group

In aldehydes, the carbonyl group is bonded to at least one hydrogen atom, and thus it occurs at the end of a chain.

18 / 20

18) In the laboratory preparation of formaldehyde, methyl alcohol vapours and air are passed over which catalyst at 300 °C?

Palladium chloride

Zinc oxide

Nickel catalyst

Platinised asbestos

Formaldehyde is prepared in the laboratory by passing a mixture of methyl alcohol vapours and air over platinised asbestos or copper or silver catalyst at 300 °C.

19 / 20

19) Which of the following functional groups is characteristic of both aldehydes and ketones?

Hydroxyl group

Ether group

Carboxyl group

Carbonyl group

Organic compounds containing the carbonyl functional group (C=O) are called carbonyl compounds, which include both aldehydes and ketones.

20 / 20

20) When naming ketones using common names, how are the alkyl groups listed?

Alphabetically

By size (largest to smallest)

In order of their attachment to the carbonyl carbon

By size (smallest to largest)

Common names of ketones list the alkyl groups in alphabetical order before the word 'ketone'.

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Aldehydes and Ketones Test. 2

1 / 20

1) How does an acid catalyst promote nucleophilic attack in carbonyl compounds?

By decreasing the electrophilic character of the carbonyl carbon

By generating a strong nucleophile

By stabilizing the negative charge on oxygen.

By increasing the electrophilic character of the carbonyl carbon atom.

An acid catalyst promotes the nucleophilic attack by increasing the positive character (electrophilic character) of the carbonyl carbon atom.

2 / 20

2) In nucleophilic addition reactions of aldehydes and ketones, the positive part of the reagent, which is usually hydrogen, goes to which atom?

The solvent

The oxygen atom of the carbonyl group

The carbon atom of the carbonyl group

An adjacent alkyl group

The positive part of the reagent, which is usually hydrogen, goes to the oxygen atom of the carbonyl group.

3 / 20

3) The characteristic reactions of carbonyl compounds are primarily:

Free radical addition reactions

Electrophilic substitution reactions

Acid-base reactions

Nucleophilic addition reactions

Most of the reactions of the carbonyl group are considered to be nucleophilic addition reactions, which are the characteristic reactions of carbonyl compounds.

4 / 20

4) What is the general characteristic reaction of carbonyl compounds like aldehydes and ketones?

Elimination

Electrophilic substitution

Nucleophilic addition

Free radical addition

Most reactions of the carbonyl group are nucleophilic addition reactions, which are characteristic of carbonyl compounds.

5 / 20

5) Which statement accurately compares the adduct formed in base-catalysed versus acid-catalysed nucleophilic addition reactions?

The adduct is different for each catalyst.

Base-catalysed reactions form a more stable adduct.

The adduct is the same for both catalysts.

Acid-catalysed reactions form a more stable adduct.

Whether the addition is base-catalysed or acid-catalysed, the adduct is the same.

6 / 20

6) Which of the following describes the role of a base catalyst in nucleophilic addition reactions?

It increases the electrophilic character of the carbonyl carbon.

It protonates the carbonyl oxygen.

It increases the nucleophilic character of the reagent.

It removes water from the reaction.

A base catalyst increases the nucleophilic character of the reagent, making it a stronger nucleophile.

7 / 20

7) In the preparation of formaldehyde in the laboratory, what is used to draw air through methyl alcohol?

A suction pump

A dropping funnel

A condenser

A heating mantle

Air is drawn through methyl alcohol with the help of a suction pump.

8 / 20

8) In nucleophilic addition reactions of aldehydes and ketones, which part of the reagent typically combines with the electrophilic carbon of the carbonyl group?

The positive part

The negative part

The neutral part

Both positive and negative parts simultaneously

In these reactions, the negative part of the reagent combines with the electrophilic carbon of the carbonyl group.

9 / 20

9) The carbonyl group possesses a σ-bond and a π-bond, allowing it to primarily undergo which type of reactions?

Rearrangement reactions

Elimination reactions

Substitution reactions

Addition reactions

The carbonyl group has a σ-bond and a π-bond, allowing it to undergo addition reactions. Most reagents react with the carbonyl group by adding to it.

10 / 20

10) How does an acid catalyst facilitate nucleophilic addition reactions?

By stabilizing the negative charge on the attacking nucleophile.

By increasing the positive character of the carbonyl carbon atom.

By decreasing the electrophilic character of the carbonyl carbon.

By generating a stronger nucleophile.

An acid catalyst promotes nucleophilic attack by increasing the electrophilic character(positive character) of the carbonyl carbon atom through protonation of the carbonyl oxygen.

11 / 20

11) The addition of hydrogen cyanide (HCN) to aldehydes and ketones results in the formation of:

Carboxylic acids

Amines

Alkenes

Cyanohydrins

Aldehydes and ketones react with hydrogen cyanide to form cyanohydrins.

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12) Acetone is prepared by the dry distillation of:

Calcium acetate

Calcium oxalate

Calcium propanoate

Calcium formate

Acetone is prepared by dry distillation of calcium acetate.

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13) The reaction: 2CH₃OH + O₂ —Pt-asbestos, 300°C→ 2H−C=O + 2H₂O represents the laboratory preparation of:

Acetone

Acetaldehyde

Ethanol

Formaldehyde

This reaction specifically shows the laboratory preparation of formaldehyde.

14 / 20

14) How does a base catalyst affect nucleophilic addition reactions of carbonyl compounds?

It facilitates the removal of the positive part of the reagent.

It increases the nucleophilic character of the reagent.

It increases the positive character of the carbonyl carbon.

It decreases the electrophilic character of the carbonyl carbon.

A base catalyst increases the nucleophilic character of the reagent.

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15) In the carbonyl group (C=O), which atom has a partial positive charge and is electrophilic?

Both carbon and oxygen atoms

Neither carbon nor oxygen atom

Carbon atom

Oxygen atom

The carbon atom in the carbonyl group has a partial positive charge and is electrophilic.

16 / 20

16) The industrial method for formaldehyde production uses a temperature of 500 °C, while the laboratory method uses:

300 °C

100 °C

400 °C

200 °C

The industrial method uses 500°C, while the laboratory method for formaldehyde uses 300°C.

17 / 20

17) The first step in a base-catalysed nucleophilic addition reaction involves:

Protonation of the carbonyl oxygen.

The base reacting with the reagent to generate the nucleophile.

Attack of an electrophile on the carbonyl carbon.

Formation of a carbocation.

A base-catalysed nucleophilic addition reaction will take place with a strong nucleophilic reagent. The base reacts with the reagent and generates the nucleophile.

18 / 20

18) In nucleophilic addition reactions, which atom of the carbonyl group is attacked by the nucleophile?

Both carbon and oxygen atoms simultaneously

Oxygen atom

Hydrogen atom (if present)

Carbon atom

The negative part of the reagent (nucleophile) combines with the electrophilic carbon of the carbonyl group.

19 / 20

19) In the addition of HCN to a carbonyl compound, the reaction is usually catalysed by:

Strong acid

Strong base

Neutral salt

Lewis acid

The addition of HCN to carbonyl compounds is usually catalysed by a strong base like NaOH or K₂CO₃. The base produces a cyanide ion (CN⁻), which is a strong nucleophile.

20 / 20

20) Why is the carbonyl group considered a polar group?

The double bond restricts electron movement.

Carbon is more electronegative than oxygen.

It has a linear geometry.

Oxygen tends to attract electrons to itself, creating partial charges.

As oxygen is more electronegative, it tends to attract the electrons to itself, making the carbonyl group a polar group.

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Aldehydes and Ketones Test. 3

1 / 20

1) The reaction of aldehydes and ketones with ammonia derivatives is considered a condensation reaction because:

It requires high pressure.

It forms a larger molecule.

Water is lost after addition occurs.

It is reversible.

This reaction is known as a condensation reaction or addition-elimination reaction because water is lost after addition occurs.

2 / 20

2) What type of compounds are formed when Grignard reagents react with aldehydes and ketones, followed by hydrolysis?

Carboxylic acids

Alcohols

Ethers

Alkanes

Grignard reagents react with aldehydes and ketones to form addition products which, on hydrolysis, yield alcohols.

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3) The reaction of aldehydes and ketones with ammonia derivatives is typically catalysed by:

Base

Heat

Light

Acid

The reaction of aldehydes and ketones with ammonia derivatives is acid catalysed.

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4) What kind of compounds are formed when aldehydes and ketones react with ammonia derivatives?

Carboxylic acids

Ethers

Compounds containing the C=N-G group and water

Alcohols

Aldehydes and ketones react with ammonia derivatives, G-NH₂, to form compounds containing the group, C=N-G and water.

5 / 20

5) The reduction of aldehydes and ketones using hydrogen in the presence of a catalyst like nickel or platinum is known as:

Hydration

Hydrogenation

Dehydration

Oxidation

The addition of hydrogen across the carbonyl group in the presence of a catalyst like nickel or platinum is called catalytic hydrogenation.

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6) The addition of sodium bisulphite is reversible. For which type of carbonyl compounds is this addition particularly useful for purification?

High molecular weight aldehydes only

Low molecular weight aldehydes and ketones

Only aromatic aldehydes

Only large ketones

Bisulphite addition products are generally crystalline solids. This reaction is particularly useful for the separation and purification of low molecular weight aldehydes and ketones from non-carbonyl compounds.

7 / 20

7) Which of the following reducing agents is generally more powerful and used for a wider range of reductions, including carboxylic acids?

LiAlH₄

Zn-Hg/HCl

NaBH₄

Na/C₂H₅OH

Lithium aluminum hydride (LiAlH₄) is a more powerful reducing agent than sodium borohydride (NaBH₄) and can reduce carboxylic acids and their derivatives, whereas NaBH₄ is selective for aldehydes and ketones.

8 / 20

8) The bisulphite addition product is generally crystalline and water-soluble. How can the original aldehyde or ketone be regenerated from it?

By heating with acid or alkali

By oxidation

By reaction with HCN

By reduction

The original aldehyde or ketone can be regenerated from the bisulphite addition product by heating with an acid or alkali. This property is used in the separation and purification of carbonyl compounds.

9 / 20

9) What type of reaction is the reduction of a carbonyl group to a hydroxyl group?

Elimination reaction

Substitution reaction

Oxidation

Addition reaction

The reduction of aldehydes and ketones is a type of addition reaction, specifically the addition of hydrogen.

10 / 20

10) Which of the following compounds would be most reactive towards nucleophilic addition?

Acetaldehyde

Diethyl ketone

Acetone

Formaldehyde

Formaldehyde (HCHO) is the most reactive aldehyde/ketone towards nucleophilic addition because it has the least steric hindrance (two hydrogen atoms attached to the carbonyl carbon) and no electron-donating alkyl groups to reduce the electrophilicity of the carbonyl carbon. Reactivity decreases as steric hindrance and electron donation increase.

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11) Ketones can be reduced to which type of alcohol?

Primary alcohol

Trihydric alcohol

Secondary alcohol

Tertiary alcohol

Ketones are reduced to secondary alcohols.

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12) Reaction of any aldehyde (other than formaldehyde) with a Grignard reagent, followed by hydrolysis, gives a:

Secondary alcohol

Tertiary alcohol

Alkene

Primary alcohol

Any aldehyde other than formaldehyde reacts with Grignard reagents to yield secondary alcohols.

13 / 20

13) Why are aldehydes generally more reactive than ketones towards nucleophilic addition reactions?

Ketones have two bulky alkyl groups increasing steric hindrance and decreasing electrophilicity.

The carbonyl carbon in aldehydes is less electrophilic.

Aldehydes are more sterically hindered.

Aldehydes have stronger C=O bonds.

Ketones are less reactive than aldehydes due to two reasons: (1) steric hindrance: ketones have two bulky alkyl groups, increasing hindrance to nucleophilic attack; (2) electronic effects: two alkyl groups in ketones release electrons, decreasing the positive charge on the carbonyl carbon and making it less electrophilic compared to aldehydes.

14 / 20

14) Which of the following is a key step in the base-catalysed addition of HCN?

Elimination of water.

Protonation of the carbonyl oxygen.

Attack by H⁺ on the carbonyl carbon.

Reaction of the base with HCN to generate CN⁻.

In the first step of base-catalysed addition of HCN, the base reacts with HCN to generate the strongly nucleophilic cyanide ion (CN⁻).

15 / 20

15) Which of the following is a common reducing agent used for the reduction of aldehydes and ketones to alcohols?

NaBH₄

Tollens' reagent

K₂Cr₂O₇

KMnO₄

Aldehydes and ketones can be reduced to alcohols by sodium borohydride (NaBH₄) or lithium aluminum hydride (LiAlH₄).

16 / 20

16) Reaction of a ketone with a Grignard reagent, followed by hydrolysis, gives a:

Primary alcohol

Secondary alcohol

Tertiary alcohol

Aldehyde

Ketones react with Grignard reagents to yield tertiary alcohols.

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17) Aldehydes can be reduced to which type of alcohol?

Tertiary alcohol

Secondary alcohol

Dihydric alcohol

Primary alcohol

Aldehydes are reduced to primary alcohols.

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18) What type of reaction involves the joining of two molecules with the elimination of a small molecule like water?

Condensation reaction

Addition reaction

Substitution reaction

Rearrangement reaction

Condensation reaction is a reaction where two or more molecules combine with the elimination of a simple molecule like water, ammonia, or an alcohol.

19 / 20

19) What is the product formed when sodium bisulphite adds to an aldehyde or ketone?

A bisulphite addition product

An insoluble solid

A carboxylic acid

An alkene

Aldehydes and ketones react with a saturated solution of sodium bisulphite (NaHSO₃) to form bisulphite addition products.

20 / 20

20) Reaction of formaldehyde with a Grignard reagent, followed by hydrolysis, gives a:

Primary alcohol

Ether

Secondary alcohol

Tertiary alcohol

Formaldehyde reacts with Grignard reagents to yield primary alcohols.

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Aldehydes and Ketones Test. 4

1 / 14

1) What is the characteristic visible change observed when an aldehyde reacts with Tollens' reagent?

Formation of a yellow precipitate.

Disappearance of purple color.

Evolution of a gas.

Formation of a silver mirror or black precipitate.

When an aldehyde is warmed with Tollens' reagent, a shining silver mirror is formed on the inner side of the test tube, or a black precipitate of silver may appear.

2 / 14

2) Which of the following is a strong oxidizing agent used to oxidize aldehydes to carboxylic acids?

NaBH₄

LiAlH₄

Acidified potassium dichromate

Sodium bisulphite

Aldehydes can be oxidized by strong oxidizing agents like acidified potassium dichromate (K₂Cr₂O₇/H₂SO₄) or potassium permanganate (KMnO₄).

3 / 14

3) Fehling's solution consists of two solutions, Fehling's solution A and Fehling's solution B. What is Fehling's solution B?

Alkaline solution of sodium potassium tartrate

Aqueous copper sulfate

Ammoniacal silver nitrate

Dilute nitric acid

Fehling's solution B is an alkaline solution of sodium potassium tartrate (Rochelle salt). Fehling's solution A is an aqueous solution of copper sulfate.

4 / 14

4) Tollens' reagent is an ammoniacal solution of:

Cupric oxide

Silver nitrate

Lead acetate

Ferric chloride

Tollens' reagent is an ammoniacal solution of silver nitrate.

5 / 14

5) Which reagent is commonly used to distinguish between aldehydes and ketones due to its ability to oxidize aldehydes but not most ketones?

Grignard reagent

Tollens' reagent

Sodium borohydride

Hydrogen cyanide

Tollens' reagent is a mild oxidizing agent that oxidizes aldehydes but generally not ketones, making it useful for distinguishing between them.

6 / 14

6) Why are aldehydes more easily oxidized than ketones?

Because of the presence of an alkyl group.

Because of steric hindrance.

Because of the presence of a hydrogen atom directly attached to the carbonyl carbon.

Because ketones have stronger C=O bonds.

Aldehydes are easily oxidized because they contain a hydrogen atom attached to the carbonyl carbon. Ketones lack this hydrogen atom, making them more resistant to oxidation.

7 / 14

7) Which reduction method for aldehydes and ketones involves the use of sodium and ethanol?

Catalytic hydrogenation

Wolff-Kishner reduction

Bouveault-Blanc reduction

Clemmensen reduction

The reduction of aldehydes and ketones using sodium and ethanol is known as the Bouveault-Blanc reduction.

8 / 14

8) The reduction of ethanal will yield:

Methane

Ethanoic acid

Ethane

Ethanol

Ethanal is an aldehyde; aldehydes reduce to primary alcohols. Ethanal reduces to ethanol.

9 / 14

9) When an aldehyde is oxidized by Fehling's solution, what characteristic change is observed?

Formation of a yellow solution.

Disappearance of blue color and formation of a red precipitate.

Formation of a silver mirror.

Evolution of carbon dioxide.

Fehling's solution is a deep blue alkaline solution of cupric ions. When warmed with an aldehyde, the blue color disappears, and a red precipitate of cuprous oxide (Cu₂O) is formed.

10 / 14

10) Aldehydes are generally oxidized to which class of compounds?

Carboxylic acids

Esters

Alcohols

Alkenes

Aldehydes are readily oxidized to carboxylic acids containing the same number of carbon atoms.

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11) The Haloform reaction is a specific oxidation reaction that detects the presence of:

secondary alcohols

Carboxylic acids

All aldehydes

All ketones

The haloform reaction (e.g., iodoform test) is used to detect the presence of methyl ketones (compounds containing a CH₃-C(=O)- group) or secondary alcohols that can be oxidized to methyl ketones.

12 / 14

12) Ketones can be oxidized under vigorous conditions (strong oxidizing agents and high temperature) resulting in the cleavage of C-C bonds adjacent to the carbonyl group. What is the usual outcome regarding the number of carbon atoms in the products?

A mixture of carboxylic acids with fewer carbon atoms than the original ketone.

Alkenes with fewer carbon atoms.

Products with more carbon atoms than the original ketone.

Products with the same number of carbon atoms as the original ketone.

Under vigorous conditions, ketones undergo oxidation by the breaking of C-C bonds adjacent to the carbonyl group, forming a mixture of carboxylic acids with fewer carbon atoms than the original ketone.

13 / 14

13) When 2-propanone (acetone) is reduced, what is the product formed?

Propane

2-propanol

1-propanol

Propanal

Acetone is a ketone; ketones reduce to secondary alcohols. 2-propanone reduces to 2-propanol.

14 / 14

14) The general equation for the reduction of an aldehyde to a primary alcohol can be represented as:

R-C(=O)-R' + 2[H] → R-CH(OH)-R'

R-CH₂OH → R-CHO + H₂

R-CHO + [O] → R-COOH

R-CHO + 2[H] → R-CH₂OH

This equation shows the addition of two hydrogen atoms to an aldehyde to form a primary alcohol.

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The average score is 53%

Most Important Aldehydes And Ketones Quiz Test Online

Aldehydes And Ketones Quiz Test Online

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