Question 1

Which of the following best describes enantiomers?

Accepted Answer

They are stereoisomers that are non-superimposable mirror images of each other.

Question 2

Given a monosaccharide with 4 chiral centers, how many possible stereoisomers exist for this molecule?

Accepted Answer

$$2^4 = 16$

Question 3

Which of the following statements is TRUE regarding diastereomers?

Accepted Answer

Diastereomers are stereoisomers that are not mirror images of each other.

Question 4

A carbohydrate has the following Fischer projection. If you switch the configuration at only one chiral center, what type of stereoisomer do you create?

Accepted Answer

A diastereomer

Question 5

Which of the following pairs are enantiomers?

Accepted Answer

Two molecules that are non-superimposable mirror images of each other

Question 6

How many chiral centers are present in the following structure of xylose?

Accepted Answer

3

Question 7

If a carbohydrate has 3 chiral centers, how many possible stereoisomers can be formed?

Accepted Answer

$$2^3 = 8$

Question 8

Which of the following best describes the relationship between D-xylose and L-xylose?

Accepted Answer

They are enantiomers.

Question 9

A student is asked to draw the enantiomer of a given carbohydrate. Which of the following steps must they perform?

Accepted Answer

Invert the configuration at every chiral center.

Question 10

Which of the following is a correct formula for calculating the number of possible stereoisomers for a molecule with $$n$$ chiral centers?

Accepted Answer

$$2^n$$

Question 11

Which of the following statements about stereoisomers is FALSE?

Accepted Answer

Enantiomers have different molecular formulas.

Question 12

If a carbohydrate has 5 chiral centers, how many diastereomers can it have?

Accepted Answer

It depends on the specific structure, but the maximum number of diastereomers is $$2^5 - 2 = 30$ (excluding the enantiomeric pair).

Question 13

Which of the following best describes the difference between D- and L- monosaccharides?

Accepted Answer

They are mirror images of each other and differ at every chiral center.

Question 14

Which of the following is NOT a characteristic of enantiomers?

Accepted Answer

They have different connectivity between atoms.

Question 15

A carbohydrate with the formula $$C_5H_{10}O_5$ has three chiral centers. How many stereoisomers are possible?

Accepted Answer

$$2^3 = 8$

Question 16

Which of the following pairs are diastereomers?

Accepted Answer

Two molecules that differ at one or more (but not all) chiral centers

Question 17

Which of the following is the correct definition of a chiral center?

Accepted Answer

A carbon atom bonded to four different groups

Question 18

If a molecule has two chiral centers, how many stereoisomers are possible?

Accepted Answer

$$2^2 = 4$

Question 19

Which of the following best explains why enantiomers have identical physical properties except for optical activity?

Accepted Answer

Because they have the same molecular formula and connectivity but differ in spatial arrangement

Question 20

Which of the following is a real-world application of distinguishing between enantiomers and diastereomers?

Accepted Answer

The effectiveness and safety of pharmaceutical drugs, as one enantiomer may be therapeutic while the other is inactive or harmful.

Enantiomers and Diastereomers in Carbohydrates

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