Deck 15: The Three-Dimensional Shape of Molecules

Question 1

Which molecule is chiral?

A)
B)
C)
D)

Answer 1

C

Question 2

How many chirality centers does the following molecule contain?

A)1
B)2
C)3
D)8

Answer 2

B

Question 3

How many chirality centers does the following molecule contain?

A)0
B)1
C)2
D)3

Answer 3

B

Question 4

Consider the stereoisomers (A-E)drawn below: Which structure is an enantiomer of structure A?

A)structure B
B)structure C
C)structure D
D)structure E

Question 5

Consider the stereoisomers (A-E)drawn below: Which structure(s)is/are a diastereomer of structure C?

A)structure A
B)structure B
C)structure D
D)structure E
E)None of the structures is a diastereomer of structure C.

Question 6

Which molecule is not an enantiomer of the molecule whose structure is shown below?

A)
B)
C)
D)All the molecules above are enantiomers of the original structure.

Question 7

Which molecule is an enantiomer of the one shown below?

A)
B)
C)
D)None of the molecules above is an enantiomer of the original molecule.

Question 8

What is always true about compounds related as isomers?

A)They differ in the way that atoms are connected to one another.
B)They have different functional groups.
C)They have the same molecular formula.
D)They are mirror images of each other.
E)All of the statements above are correct.

Question 9

How many chirality centers does the following molecule contain?

A)0
B)1
C)2
D)3

Question 10

How are the two compounds below related to each other?

A)They are identical molecules.
B)They are constitutional isomers.
C)They are enantiomers.
D)They are diastereomers.

Question 11

The Fischer projection formula for D-mannose, a hexose sugar, is shown below. How many chirality centers are in D-mannose?

A)2
B)4
C)5
D)6

Question 12

Diastereomers are stereoisomers that are

A)mirror images of each other.
B)not mirror images of each other.
C)nonsuperimposable mirror images of each other.
D)superimposable on each other.

Question 13

Which object is chiral?

A)a sock
B)a shoe
C)a baseball
D)a fork
E)More than one of the objects above is chiral.

Question 14

Which molecule is chiral?

A)
B)
C)
D)

Question 15

How many chirality centers are present in the compound below?

A)0
B)1
C)2
D)3
E)5

Question 16

Which, if any, of the labeled carbon atoms in the compound below is a chirality center?

A)C1 is a chirality center and C2 is not a chirality center.
B)C1 is not a chirality center and C2 is a chirality center.
C)C1 and C2 are both chirality centers.
D)Neither C1 nor C2 are chirality centers.

Question 17

Which molecule is chiral?

A)1-pentanol
B)cyclopentanol
C)2-methylcyclopentanol
D)2-methylpentane
E)More than one of the molecules above is chiral.

Question 18

Which, if any, of the labeled carbon atoms in the compound below is a chirality center?

A)C1 is a chirality center and C2 is not a chirality center.
B)C1 is not a chirality center and C2 is a chirality center.
C)C1 and C2 are both chirality centers.
D)Neither C1 nor C2 are chirality centers.

Question 19

Consider the stereoisomers (A-E)drawn below: Structures A and C are related as _____.

A)identical molecules
B)enantiomers
C)constitutional isomers
D)diastereomers

Question 20

Consider the stereoisomers (A-E)drawn below: Which structure(s)is/are diastereomers of structure E?

A)structure A
B)structure B
C)structure C
D)structure D
E)structures A and B

Question 21

Which is NOT another name for a chirality center?

A)stereogenic center
B)chiral carbon
C)asymmetric carbon
D)tetravalent carbon

Question 22

Which nonsteroidal anti-inflammatory drug(s)(NSAID)is/are sold as a racemic mixture?

A)Naproxen
B)Ibuprofen
C)Both Naproxen and Ibuprofen are sold as a racemic mixture.
D)Neither Naproxen nor Ibuprofen are sold as a racemic mixture.

Question 23

How many enantiomers can a chiral stereoisomer have?

A)0
B)1
C)2
D)The number of enantiomers depends on the number of chirality centers.

Question 24

Which statement is not true?

A)A molecule that is not superimposable on its mirror image is a chiral molecule.
B)Enantiomers are mirror images that are not superimposable.
C)A carbon atom surrounded by four different groups is a chirality center.
D)A racemic mixture contains an equal mixture of two diastereomers.

Question 25

How are the Fischer projections below related?

A)identical molecules
B)enantiomers
C)constitutional isomers
D)diastereomers

Question 26

The drug L-Dopa

A)is marketed as a racemic mixture for the treatment of Parkinson's disease.
B)was first isolated from the leaves of the broad bean Vicia faba.
C)is a chiral molecule with two chirality centers.
D)has only one enantiomer that is active against Parkinson's disease.

Question 27

In a Fischer projection,

A)horizontal lines represent bonds that come out of the plane on wedges, and the vertical lines represent bonds that go back on dashed lines.
B)vertical lines represent bonds that come out of the plane on wedges, and the horizontal lines represent bonds that go back on dashed lines.
C)horizontal lines represent bonds that are in the plane of the paper, and the vertical lines represent bonds that go back on dashed lines.
D)vertical lines represent bonds that are in the plane of the paper, and the horizontal lines represent bonds that go back on dashed lines.

Question 28

Penicillamine is used to treat arthritis. How many chirality centers are present in penicillamine?

A)0
B)1
C)2
D)3
E)more than 3

Question 29

Consider the stereoisomers (A-E)drawn below: Structures C and D are _____.

A)identical molecules
B)enantiomers
C)constitutional isomers
D)diastereomers

Question 30

What property is the odor of a molecule most dependent on?

A)the functional groups present in the molecule
B)the shape of the molecule
C)whether a molecule can form hydrogen bonds
D)the number of carbons in the molecule

Question 31

Compounds related as constitutional isomers have

A)the same number of chirality centers.
B)the same functional groups.
C)the same molecular formulas.
D)the same smell.
E)All of the statements above are true.

Question 32

Alanine, shown below, is a naturally occurring chiral amino acid. Which pair represents the two enantiomers of alanine?

A) and
B) and
C) and

Question 33

Which structure represents the three-dimensional structure of the Fischer projection shown?

A)
B)
C)
D)

Question 34

Which compound has the most stereoisomers?

A)
B)
C)
D)
E)

Question 35

Penicillamine is used to treat arthritis. How many chirality centers are present in penicillamine?

A)0
B)1
C)2
D)3
E)more than 3

Question 36

Enantiomers are stereoisomers that are

A)mirror images of each other that are identical.
B)not mirror images of each other.
C)nonsuperimposable mirror images of each other.
D)cis-trans isomers of each other.

Question 37

How many diastereomers can a chiral stereoisomer have?

A)1
B)2
C)3
D)The number of diastereomers depends on the number of chirality centers.

Question 38

Which statement is true?

A)A carbon that is part of a multiple is always a chirality center.
B)The carbon atom in a CH₂ group is a chirality center only when it is part of a ring.
C)Stereoisomers always have the same functional groups.
D)Diastereomers are mirror image isomers that are not superimposable.

Question 39

How are the structures below related?

A)identical molecules
B)enantiomers
C)constitutional isomers
D)diastereomers

Question 40

The drug Thalidomide was

A)invented by Frances Oldham Kelsey.
B)sold as a mixture of its two enantiomers, and each of these stereoisomers has a different biological activity.
C)was approved for use in the United States.
D)All of the statements above are true.

Question 41

Two enantiomers typically have the same biological activity.

Question 42

The compound 3, 6-diethyl-6-methyl-3-decanethiol is a chiral molecule with more than one chirality center.

Question 43

Which statement concerning stereochemistry is incorrect?

A)An object or molecule is chiral if it is nonsuperimposable on its mirror image.
B)A chiral molecule is optically active and rotates plane polarized light either clockwise or counterclockwise.
C)Enantiomers are superimposable mirror image isomers.
D)Diastereomers are stereoisomers that are not related as mirror images.

Question 44

Any molecule with one chirality center is a chiral compound.

Question 45

Hexane (CH₃CH₂CH₂CH₂CH₂CH₃)has a mirror image, but it does not have an enantiomer.

Question 46

Recent rulings by the Food and Drug Administration have encouraged the development of so-called racemic switches, the patenting and marketing of a single enantiomer that was originally sold as a racemic mixture.

Question 47

The specific rotation of pure cholesterol was measured to be -32. Based on this information, which statement concerning cholesterol is NOT true?

A)Cholesterol is a chiral compound.
B)Cholesterol is optically inactive.
C)Cholesterol is levorotatory.
D)Cholesterol rotates plane polarized light in a counterclockwise direction.

Question 48

cis-2-butene and trans-2-butene are enantiomers.

Question 49

Another term in common use for a chirality center is an asymmetric carbon.

Question 50

The Fischer projection shown on the right properly represents the three-dimensional compound shown on the left.

Question 51

The molecule below is achiral.

Question 52

Enantiomers are mirror images that are not superimposable.

Question 53

The Fischer projection shown on the right properly represents the ball and stick model of the compound shown on the left.

Question 54

Any molecule with two chirality centers is an achiral compound.

Question 55

Propranol, shown below, is a chiral compound that exists as a pair of enantiomers. One enantiomer is used to treat irregular heartbeats, and the other enantiomer is used as a contraceptive. Identify the chirality center(s)in Propranol.

A)C1
B)C2
C)C3
D)C4
E)C1 and C3

Question 56

A carbonyl carbon is a common example of a chirality center.

Question 57

Which property of enantiomers is not identical?

A)Melting point
B)Boiling point
C)Solubility
D)Specific rotation
E)All of the above properties are identical for a pair of enantiomers.

Question 58

Propranol, shown below, is a chiral compound that exists as a pair of enantiomers. One enantiomer is used to treat irregular heartbeats, and the other enantiomer is used as a contraceptive. Identify the chirality center(s)in Propranol.

A)C1
B)C2
C)C3
D)C4
E)C1 and C3

Question 59

Carbohydrates, lipids, proteins, and nucleic acids are all chiral biomolecules. What does the term chiral indicate about a molecule?

A)The molecule can be synthesized by the body.
B)The molecule can be digested by the body.
C)The molecule has a mirror image.
D)The molecule and its mirror image are not identical.

Question 60

The amino acid alanine found in the proteins of the body has a melting point of 297 °C and a specific rotation of +8.5. The enantiomer of alanine would have a melting point of -297 °C and a specific rotation of -8.5.

Question 61

Aspartame contains two chirality centers.

Question 62

The compounds shown below are related as constitutional isomers.

Question 63

There are six chirality centers in the simple sugar D-glucose, shown below.

Question 64

The major product of the dehydration of the alcohol below has one chirality center.

Question 65

A nail is an example of a chiral object.

Question 66

The alkyl bromide below contains one chirality center.

Question 67

The Fischer projection shown to the right represents the enantiomer of the three-dimensional structure to the left.

Question 68

A chiral molecule has at least one carbon atom that has four different substituents bonded to it.

Question 69

The compound 4-methyl-2-hexene is not a chiral molecule.

Question 70

In organic molecules, oxygen atoms cannot be chirality centers.

Question 71

If a stereoisomer has an enantiomer, it does not have a diastereomer.

Question 72

All tertiary alcohols (3°)are chiral.

Question 73

Only chiral molecules have a mirror image.

Question 74

The compounds shown below are related as constitutional isomers.

Question 75

Enantiomers may have different odors because they bind with chiral receptors and each enantiomer fits the chiral receptors in a different way.

Question 76

The Fischer projection to the right represents the compound to the left.

Question 77

Aspartame contains two chirality centers.

Question 78

A human foot is a chiral object.

Question 79

For an odor to be perceived, a molecule must bind to an olfactory receptor, resulting in a nerve impulse that travels to the brain.

Question 80

The compound 3-methylcyclopentanol contains one chirality center.