Question 1

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

Accepted Answer

An aldehyde has at least one hydrogen atom attached to the carbonyl carbon, while a ketone has two alkyl or aryl groups attached to the carbonyl carbon.

Question 2

Which of the following is the correct general formula for a carboxylic acid?

Accepted Answer

$$RCOOH$$

Question 3

What is the main visual result of a positive Tollens' test for an aldehyde?

Accepted Answer

Formation of a silver mirror on the inner surface of the test tube

Question 4

Which of the following best explains why ketones do not give a positive Fehling's test?

Accepted Answer

Ketones cannot be oxidized under the conditions of the Fehling's test because they lack a hydrogen atom on the carbonyl carbon.

Question 5

Which of the following equations correctly represents the oxidation of an aldehyde with potassium permanganate ($$KMnO_4$$)?

Accepted Answer

$$3RCHO + 2KMnO_4 + H_2O \rightarrow 3RCOOH + 2MnO_2 + 2KOH$$

Question 6

What is the product of the reaction between a carboxylic acid and sodium hydroxide ($$NaOH$$)?

Accepted Answer

$$RCOOH + NaOH \rightarrow RCOONa + H_2O$$

Question 7

Which of the following statements about the 2,4-dinitrophenylhydrazine (DNP) test is correct?

Accepted Answer

Both aldehydes and ketones give a yellow-orange precipitate with DNP.

Question 8

Which of the following best describes the nucleophilic addition mechanism to a carbonyl group?

Accepted Answer

A nucleophile attacks the electrophilic carbon of the carbonyl group, breaking the $$\pi$$ bond and forming a tetrahedral intermediate.

Question 9

What is the main product when an aldehyde reacts with Fehling's solution?

Accepted Answer

$$Cu_2O ($$red precipitate) and a carboxylate ion

Question 10

Which of the following is a correct statement about the acidity of carboxylic acids?

Accepted Answer

Carboxylic acids are more acidic than alcohols due to resonance stabilization of the carboxylate anion.

Question 11

Which of the following best explains why the carbonyl carbon is electrophilic?

Accepted Answer

The oxygen atom is more electronegative than carbon, withdrawing electron density and making the carbon partially positive.

Question 12

Which of the following is the correct balanced equation for the iodoform reaction with a methyl ketone?

Accepted Answer

$$RCOCH_3 + 3I_2 + 4$$NaOH \rightarrow RCOONa + $$CHI_3 + 3$$NaI + 3H_2O$$

Question 13

A student adds an unknown compound to Fehling's solution and observes a red precipitate. Which functional group is most likely present in the compound?

Accepted Answer

Aldehyde

Question 14

Which of the following is a necessary intermediate in the oxidation of an aldehyde to a carboxylic acid in aqueous solution?

Accepted Answer

A hydrate (geminal diol)

Question 15

Which of the following best describes the result of adding water to a carbonyl compound in acidic or basic conditions?

Accepted Answer

Formation of a hydrate (geminal diol)

Question 16

Which of the following is a correct statement about the nucleophilic acyl substitution mechanism?

Accepted Answer

A nucleophile attacks the carbonyl carbon, and a leaving group (Z) departs, forming a new acyl compound.

Question 17

Which of the following is the correct expression for the acid dissociation constant ($$K_a) of a $$carboxylic acid?

Accepted Answer

$$K_a = \frac{[A^-][H_3O^+]}{[HA]}$$

Question 18

Which of the following is a distinguishing feature of the iodoform test?

Accepted Answer

Formation of a yellow precipitate of $$CHI_3$$

Question 19

Which of the following best explains why carboxylic acids can change the color of acid-base indicators?

Accepted Answer

Carboxylic acids are weak acids that partially ionize in water, lowering the pH and causing a color change in indicators.

Characteristic Reactions of Functional Groups: Aldehydes, Ketones, and Carboxylic Acids

Study Guide - Practice Questions

Study Guide - Flashcards