Question 1

Which of the following statements best describes a chiral molecule?

Accepted Answer

A molecule that is non-superimposable with its mirror image.

Question 2

A carbon atom is considered a chiral center if:

Accepted Answer

It is bonded to four different groups.

Question 3

Which of the following compounds is achiral?

Accepted Answer

A molecule with a plane of symmetry.

Question 4

Which of the following best describes enantiomers?

Accepted Answer

They are non-superimposable mirror images.

Question 5

A sample of 2-butanol has a specific rotation of $$+7.0^\circ. If $$the specific rotation of pure $$(-)-2-$$butanol is $$-13.5^\circ$$, what is the enantiomeric excess (ee) of the mixture?

Accepted Answer

$$51.9\%$$

Question 6

Which of the following statements about racemic mixtures is correct?

Accepted Answer

They contain equal amounts of both enantiomers.

Question 7

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

Accepted Answer

$$2^3 = 8$

Question 8

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

Accepted Answer

Both enantiomers rotate plane-polarized light by the same magnitude but in opposite directions.

Question 9

Assign priorities to the following groups attached to a chiral carbon: $$-OH$$, $$-CH_3$, -H$, -Br$. Which group has the highest priority according to the Cahn-Ingold-Prelog rules?

Accepted Answer

$$-Br$$

Question 10

A solution of glucose in water in a 10 cm polarimeter tube shows a rotation of $$+15.8^\circ. If $$the specific rotation of glucose is $$+52.8^\circ$$, what is the concentration of glucose in $$g/mL$$?

Accepted Answer

$$0.299\ g/mL$$

Question 11

Which of the following statements about meso compounds is correct?

Accepted Answer

Meso compounds are achiral despite having chiral centers.

Question 12

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

Accepted Answer

They are diastereomers.

Question 13

Which of the following molecules is chiral?

Accepted Answer

A molecule with a carbon bonded to four different groups.

Question 14

Which of the following is NOT a property of diastereomers?

Accepted Answer

They have identical chemical reactivity in all environments.

Question 15

Which of the following statements about Fischer projections is FALSE?

Accepted Answer

A 180° rotation in the plane of the paper changes the configuration.

Question 16

Which of the following is the correct formula for calculating specific rotation?

Accepted Answer

$$[\alpha]^t_\lambda = \frac{\alpha_{	ext{observed}}}{c 	imes l}$$

Question 17

Which of the following is true about the separation of enantiomers?

Accepted Answer

Enantiomers can be separated by reacting with a pure chiral compound to form diastereomers.

Question 18

Which of the following molecules can be chiral even without a chiral carbon center?

Accepted Answer

Biphenyls with bulky ortho substituents.

Question 19

Which of the following is the correct definition of enantiomeric excess (ee)?

Accepted Answer

$$ee = \frac{	ext{amount of major enantiomer} - 	ext{amount of minor enantiomer}}{	ext{total amount}} 	imes 100\%$$

Question 20

Which of the following statements about the R/S system is correct?

Accepted Answer

The R configuration is assigned when the sequence from highest to lowest priority is clockwise, with the lowest priority group in the back.

Stereochemistry: Chirality, Enantiomers, and Stereoisomerism

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