Question 1

Which of the following statements best distinguishes stereoisomers from constitutional isomers?

Accepted Answer

Stereoisomers have the same molecular formula and connectivity but differ in the spatial arrangement of atoms.

Question 2

Which of the following molecules is chiral?

Accepted Answer

A carbon atom bonded to four different groups.

Question 3

A compound has two chiral centers. What is the maximum number of possible stereoisomers for this compound?

Accepted Answer

$$2^2 = 4$

Question 4

Which of the following best describes a meso compound?

Accepted Answer

A compound with chiral centers that is achiral due to a plane of symmetry.

Question 5

When assigning priorities for the Cahn-Ingold-Prelog system, which rule is followed?

Accepted Answer

The atom with the highest atomic number receives the highest priority.

Question 6

Which of the following is true regarding the optical activity of enantiomers?

Accepted Answer

Enantiomers rotate plane-polarized light to equal degrees in opposite directions.

Question 7

A racemic mixture contains equal amounts of two enantiomers. What is the expected optical rotation of this mixture?

Accepted Answer

$$0^\circ$$

Question 8

Which of the following methods is commonly used to resolve (separate) enantiomers in a laboratory setting?

Accepted Answer

Affinity chromatography using a chiral adsorbent.

Question 9

Which statement about the relationship between R/S configuration and optical rotation (+/–) is correct?

Accepted Answer

There is no direct correlation between R/S configuration and the direction of optical rotation.

Question 10

Which of the following is true about diastereomers?

Accepted Answer

Diastereomers are stereoisomers that are not mirror images and have different physical properties.

Question 11

A sample contains 70% of one enantiomer and 30% of its mirror image. What is the enantiomeric excess (ee) of the sample?

Accepted Answer

$$ee = 70\% - 30\% = 40\%$$

Question 12

Which of the following is a correct statement about the E/Z system for alkenes?

Accepted Answer

E/Z notation is used when each carbon of the double bond has two different groups attached.

Question 13

Which of the following best describes a chiral compound that lacks a chiral center?

Accepted Answer

A compound with an axis of chirality, such as certain atropisomers or allenes.

Question 14

Which of the following statements about rotational and reflectional symmetry is correct?

Accepted Answer

The presence or absence of rotational symmetry is irrelevant to chirality.

Question 15

Which of the following is true about the physical properties of enantiomers?

Accepted Answer

Enantiomers have identical physical properties except for their interaction with plane-polarized light and other chiral compounds.

Question 16

Which of the following is a correct step in assigning R/S configuration to a chiral center?

Accepted Answer

Arrange the molecule so the lowest priority group is facing away from you.

Question 17

Which of the following statements is true regarding the interconversion of conformations and optical activity?

Accepted Answer

If two conformations are rapidly interconverting and are nonsuperimposable mirror images, the compound is not optically active.

Question 18

Which of the following is a real-world example of the importance of chirality in pharmacology?

Accepted Answer

Two enantiomers of a drug may have very different biological effects.

Question 19

Which of the following is true about Fischer projections?

Accepted Answer

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

Stereoisomerism in Organic Chemistry: Concepts, Classification, and Applications

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