Question 1

Which of the following statements best explains why formaldehyde (methanal) is commonly used to preserve biological specimens, as shown in the image?

Accepted Answer

Formaldehyde contains a highly reactive carbonyl group that cross-links proteins, preventing decay.

Question 2

Which of the following compounds is an aldehyde?

Accepted Answer

$$\mathrm{CH_3CH_2CHO}$$

Question 3

What is the IUPAC name for the compound shown below?

$$\mathrm{CH_3CH_2CH_2CHO}$$

Accepted Answer

Butanal

Question 4

Which of the following best describes the difference between an aldehyde and a ketone?

Accepted Answer

Aldehydes have a carbonyl group bonded to at least one hydrogen, while ketones have a carbonyl group bonded to two alkyl groups.

Question 5

Which of the following compounds will give a positive Tollens’ test?

Accepted Answer

$$\mathrm{CH_3CH_2CHO} ($$propanal)

Question 6

Which of the following best explains why acetone (propanone) is more soluble in water than hexanone?

Accepted Answer

Acetone has a smaller nonpolar region, allowing its carbonyl group to form hydrogen bonds with water.

Question 7

Which of the following is the correct product of the reduction of butanone ($$\mathrm{CH_3COCH_2CH_3}) $$with $$\mathrm{H_2$}$$ and a nickel catalyst?

Accepted Answer

$$\mathrm{CH_3CH(OH)CH_2CH_3}$$

Question 8

Which of the following compounds is most likely to be found as a cyclic hemiacetal in aqueous solution?

Accepted Answer

Glucose

Question 9

Which of the following best explains why aldehydes are generally more reactive than ketones toward nucleophilic addition?

Accepted Answer

Aldehydes have a more positive carbonyl carbon due to less electron-donating alkyl groups.

Question 10

Which of the following best describes the product formed when an aldehyde reacts with one equivalent of an alcohol in the presence of acid?

Accepted Answer

A hemiacetal

Question 11

Which of the following compounds will give a positive Benedict’s test?

Accepted Answer

2-Hydroxypropanal

Question 12

What is the IUPAC name for the following compound?

$$\mathrm{C_6H_5CHO}$$

Accepted Answer

Benzaldehyde

Question 13

Which of the following best explains why the boiling point of propanone is higher than that of propane, but lower than that of 1-propanol?

Accepted Answer

Propanone has dipole-dipole interactions, but cannot hydrogen bond with itself like 1-propanol.

Question 14

Which of the following is the correct IUPAC name for the compound shown below?

$$\mathrm{CH_3CH_2COCH_3}$$

Accepted Answer

Butanone

Question 15

Which of the following best describes the product when glucose reacts with Benedict’s reagent?

Accepted Answer

Gluconic acid and $$\mathrm{Cu_2O} ($$brick red solid)

Question 16

Which of the following is the correct product when cyclohexanone is reduced with $$\mathrm{H_2$}$$ and a nickel catalyst?

Accepted Answer

Cyclohexanol

Question 17

Which of the following best describes the structure of an acetal?

Accepted Answer

A carbon atom bonded to two –OR groups

Question 18

Which of the following is a real-life application of the formation of cyclic acetals from cyclic hemiacetals?

Accepted Answer

Formation of disaccharides such as maltose from glucose units

Question 19

Which of the following best explains why 3-pentanone is only slightly soluble in water, while propanone is very soluble?

Accepted Answer

3-Pentanone has a larger nonpolar region, reducing its ability to hydrogen bond with water.

Aldehydes and Ketones: Structure, Properties, and Reactions

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