Question 1

Which of the following statements best describes a chiral molecule?

Accepted Answer

A molecule whose mirror image is nonsuperimposable on the original molecule.

Question 2

Which of the following compounds is most likely to be achiral?

Accepted Answer

A compound with a plane of symmetry.

Question 3

According to the Cahn-Ingold-Prelog priority rules, which of the following groups has the highest priority when attached to a stereocenter carbon?

Accepted Answer

$$\mathrm{Br}$$

Question 4

Which of the following best describes the relationship between the two molecules shown below? (One is the mirror image of the other, both have opposite configurations at all chiral centers.)

Accepted Answer

Enantiomers

Question 5

A sample of (R)-2-butanol rotates plane-polarized light by $$-13.5^\circ. $$What will be the observed optical rotation if you have a racemic mixture of (R)-2-butanol and (S)-2-butanol?

Accepted Answer

$$0^\circ$$

Question 6

Which of the following statements about enantiomers is FALSE?

Accepted Answer

They have different physical properties such as density and refractive index.

Question 7

How many stereoisomers are possible for a molecule with three chiral centers, assuming there is no plane of symmetry?

Accepted Answer

$$2^3 = 8$

Question 8

Which of the following best describes a meso compound?

Accepted Answer

A compound with a plane of symmetry and is achiral despite having chiral centers.

Question 9

Which of the following is NOT a property of diastereomers?

Accepted Answer

They are non-superimposable mirror images.

Question 10

A molecule has the following configuration at its only chiral center: the priorities are assigned as Br (1), NH$$_2 (2$$), CH$$_3 (3$$), and H (4). If the lowest priority group (H) is on a dashed wedge, and the sequence from 1 to 2 to 3 is clockwise, what is the absolute configuration?

Accepted Answer

(R)

Question 11

Which of the following statements about the separation of enantiomers and diastereomers is correct?

Accepted Answer

Diastereomers can be separated by physical methods due to their different physical properties.

Question 12

Which of the following best describes the Cahn-Ingold-Prelog priority rule for assigning configuration at a stereocenter?

Accepted Answer

Assign priorities based on atomic number; higher atomic number gets higher priority.

Question 13

Which of the following is true about the optical activity of a racemic mixture?

Accepted Answer

It does not rotate plane-polarized light.

Question 14

Which of the following molecules is chiral?

Accepted Answer

A molecule with a carbon atom bonded to four different groups.

Question 15

Which of the following is a correct statement about Fischer projections?

Accepted Answer

Horizontal lines represent bonds coming out of the plane toward the viewer.

Question 16

Which of the following is a real-world consequence of chirality in organic molecules?

Accepted Answer

Most enzymes are stereospecific and only bind one enantiomer.

Question 17

Which of the following best describes the relationship between cis-1,2-dichlorocyclohexane and trans-1,2-dichlorocyclohexane?

Accepted Answer

They are diastereomers.

Question 18

Which of the following is true about the chirality of allenes?

Accepted Answer

Allenes can be chiral if the groups at the end carbons are different.

Question 19

A molecule has two chiral centers. One stereoisomer is (2R,3S), and another is (2S,3S). What is the relationship between these two molecules?

Accepted Answer

They are diastereomers.

Stereochemistry: Chirality, Enantiomers, Diastereomers, and Isomerism

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