Question 1

Which of the following statements best describes a chiral molecule?

Accepted Answer

A molecule that is not superimposable on its mirror image.

Question 2

How many stereoisomers are possible for a molecule with three asymmetric centers?

Accepted Answer

$$2^3 = 8$

Question 3

Which of the following is true about enantiomers?

Accepted Answer

They have identical physical properties except for their interaction with plane-polarized light.

Question 4

A molecule with the following structure has how many chiral centers?

$$\mathrm{CH_3CH(OH)CH_2OH}$$

Accepted Answer

1

Question 5

Which of the following best describes a meso compound?

Accepted Answer

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

Question 6

What is the configuration (R or S) of the following chiral center?

$$\mathrm{CH_3CH_2CH(CH_3$)H} ($$with the hydrogen on a wedge)

Accepted Answer

S

Question 7

Which of the following is NOT a configurational isomer?

Accepted Answer

conformational isomers

Question 8

A racemic mixture is best described as:

Accepted Answer

A mixture containing equal amounts of both enantiomers.

Question 9

Which of the following drugs caused birth defects due to the presence of both enantiomers in a racemic mixture?

Accepted Answer

Thalidomide

Question 10

Which of the following is the correct order of priority for assigning R/S configuration according to the Cahn-Ingold-Prelog rules?

Accepted Answer

$$\mathrm{Cl \u003e F \u003e O \u003e N \u003e C \u003e H \u003e e^-}$$

Question 11

Which of the following statements is true about diastereomers?

Accepted Answer

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

Question 12

Which of the following compounds is achiral?

Accepted Answer

A compound with a plane of symmetry.

Question 13

If a compound has two chiral centers and a plane of symmetry, how many stereoisomers are possible?

Accepted Answer

3 (including a meso compound)

Question 14

Which of the following is true about optical activity?

Accepted Answer

Racemic mixtures are optically inactive.

Question 15

Which of the following is a real-world consequence of not separating enantiomers in pharmaceuticals?

Accepted Answer

Unintended physiological effects, such as birth defects.

Question 16

Which of the following is the correct definition of a stereocenter?

Accepted Answer

An atom bonded to four different groups.

Question 17

Which of the following statements is true regarding the physical properties of enantiomers?

Accepted Answer

They have identical boiling points and solubility in achiral solvents.

Question 18

Which of the following is the correct relationship between the optical rotations of a pair of enantiomers?

Accepted Answer

They have equal magnitude and opposite direction.

Question 19

Which of the following is a property of a racemic mixture?

Accepted Answer

It is optically inactive.

Question 20

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

Accepted Answer

$$2^n$$

Ch 5

Study Guide - Practice Questions