Question 1

Which of the following statements best describes a reducing sugar?

Accepted Answer

A carbohydrate that produces a sugar acid upon oxidation in a basic solution.

Question 2

When D-glucose is treated with Benedict's reagent, what is the expected product?

Accepted Answer

D-gluconic acid

Question 3

Which equation correctly represents the oxidation of an aldose monosaccharide in Benedict's test?

Accepted Answer

$$ \mathrm{R{-}CHO} + 2\,Cu$$^{2+}$$ + 5\,OH^- \rightarrow \mathrm{R{-}COOH} + Cu_2O + 3\,H_2O $$

Question 4

Which of the following is NOT a property of reducing sugars?

Accepted Answer

They cannot be oxidized by copper(II) ions.

Question 5

In a basic solution, which functional group of an aldose monosaccharide is oxidized?

Accepted Answer

The aldehyde group

Question 6

Which of the following is the correct product when D-glucose is reduced?

Accepted Answer

D-glucitol (sorbitol)

Question 7

Which statement is TRUE regarding ketoses in Benedict's test?

Accepted Answer

Ketoses are converted to aldoses in basic solution and then oxidized.

Question 8

What is the common name for the reduction product of D-glucose?

Accepted Answer

D-glucitol (sorbitol)

Question 9

Which of the following best explains why all aldose and ketose monosaccharides are considered reducing sugars in basic solution?

Accepted Answer

Because ketoses can tautomerize to aldoses, which are then oxidized.

Question 10

Which of the following is the correct sequence of products when D-glucose undergoes oxidation and reduction?

Accepted Answer

D-gluconic acid (oxidation), D-glucitol (reduction)

Question 11

A patient’s urine sample gives a positive Benedict’s test. Which of the following is the most likely explanation?

Accepted Answer

The urine contains a reducing sugar such as glucose.

Question 12

Which of the following equations represents the reduction of D-glucose?

Accepted Answer

$$ \mathrm{D{-}glucose} + 2\,H_2$ \rightarrow \mathrm{D{-}glucitol} $$

Question 13

Which of the following is a correct statement about the products of D-glucose oxidation and reduction?

Accepted Answer

Oxidation produces D-gluconic acid; reduction produces D-glucitol.

Question 14

Which of the following statements is FALSE regarding Benedict's test?

Accepted Answer

It cannot detect ketose sugars.

Question 15

Which of the following is the correct product when D-galactose is oxidized in a basic solution?

Accepted Answer

D-galactonic acid

Question 16

Which of the following is a correct statement about the reaction of D-glucose with copper(II) ions in Benedict's test?

Accepted Answer

D-glucose is oxidized to D-gluconic acid.

Question 17

Which of the following best describes the chemical change that occurs when an aldose is oxidized in Benedict's test?

Accepted Answer

The aldehyde group is converted to a carboxylic acid group.

Question 18

Which of the following is the correct product when D-glucose is reduced with hydrogen?

Accepted Answer

D-glucitol (sorbitol)

Question 19

Which of the following is the correct name for the oxidation product of D-mannose?

Accepted Answer

D-mannonic acid

Oxidation and Reduction of Monosaccharides: Reducing Sugars and Benedict's Test

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