Deck 15: The Three-Dimensional Shape of Molecules

Question 1

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

Answer 1

not mirror images of each other

Question 2

How many chirality centers does the following molecule contain?

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

Answer 2

2

Question 3

Two enantiomers rotate plane-polarized light ________.

A)to an equal extent but in opposite directions
B)to an equal extent in the same direction
C)to vastly differing extents in random directions
D)exactly 90º clockwise

Answer 3

to an equal extent but in opposite directions

Question 4

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

A)C1 is the only chirality center.
B)C2 is the only chirality center.
C)Both C1 and C2 are chirality centers.
D)Neither C1 nor C2 are chirality centers.

Question 5

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

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

Question 6

Which molecule is chiral?

A)
B)
C)
D)

Question 7

How many chirality centers are present in the compound below?

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

Question 8

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

A)C1 is the only chirality center.
B)C2 is the only chirality center.
C)Both C1 and C2 are chirality centers.
D)Neither C1 nor C2 are chirality centers.

Question 9

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 10

How can the following molecules be classified correctly?

A)II and III are identical molecules
B)I and II are constitutional isomers
C)I and III are stereoisomers
D)II and III are stereoisomers
E)Both statements B and D are correct

Question 11

How many chirality centers does the following molecule contain?

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

Question 12

Which molecule is an enantiomer of the one shown below?

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

Question 13

How many chirality centers does the following molecule contain?

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

Question 14

Which object is chiral?

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

Question 15

Which molecule is chiral?

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

Question 16

Which molecule is chiral?

A)
B)
C)
D)

Question 17

Which choice is not one of the properties that are identical for two enantiomers of the same compound?

A)Melting point
B)Interaction with plane-polarized light
C)Boiling point
D)Solubility
E)None of the choices are correct.

Question 18

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

A)C2 is the only chirality center.
B)C2,C3,and C4 and all chirality centers.
C)C3 and C4 are both chirality centers
D)C2 and C4 and both chirality centers
E)C1 and C3 are both chirality centers

Question 19

Which choice is the enantiomer of the molecule given below?

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

Question 20

A compound that does not change the direction of plane-polarized light is called

A)Chiral
B)Diastereomer
C)Achiral
D)Neutral
E)Acidic

Question 21

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 22

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 23

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 24

How are the Fischer projections below related?

A)Identical molecules
B)Enantiomers
C)Constitutional isomers
D)Diastereomers

Question 25

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 26

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 27

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 28

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 29

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 30

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

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

Question 31

The Fischer projection for threose,a tetrose sugar,is shown below. How many chirality centers are in threose?

A)1
B)3
C)2
D)4

Question 32

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 33

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 34

Which is NOT another name for a chirality center?

A)Stereogenic center
B)Chiral carbon
C)Asymmetric carbon
D)Tetravalent carbon

Question 35

Which choice shows the given molecule correctly represented as a Fischer projection?

A)
B)
C)
D)

Question 36

Which statement is true?

A)A carbon that is part of a multiple bond 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 37

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 38

How many chirality centers are present in the following molecule?

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

Question 39

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 choices are correct.

Question 40

Which compound has the most stereoisomers?

A)
B)
C)
D)
E)

Question 41

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 42

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 43

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 44

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

A)
B)
C)

Question 45

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 46

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

A)
B)
C)
D)

Question 47

Carvone,shown below,is a chiral compound that exists as a pair of enantiomers. One enantiomer has the odor of caraway,and the other enantiomer has the odor of spearmint. Identify the chirality center(s)in carvone.

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

Question 48

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 49

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

Question 50

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

Question 51

Any molecule with two chirality centers is an achiral compound.

Question 52

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 53

Enantiomers are mirror images that are not superimposable.

Question 54

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

Question 55

Two enantiomers typically have the same biological activity.

Question 56

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 57

Which property of enantiomers is not identical?

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

Question 58

Any molecule with one chirality center is a chiral compound.

Question 59

The molecule below is achiral.

Question 60

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

Question 61

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

Question 62

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

Question 63

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

Question 64

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

Question 65

All tertiary alcohols (3°)are chiral.

Question 66

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

Question 67

The alkyl bromide below contains one chirality center.

Question 68

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

Question 69

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

Question 70

A human foot is a chiral object.

Question 71

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

Question 72

The compound 3-methylcyclopentanol contains one chirality center.

Question 73

In organic molecules,oxygen atoms cannot be chirality centers.

Question 74

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

Question 75

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

Question 76

Aspartame contains two chirality centers.

Question 77

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

Question 78

The dipeptide molecule shown below contains two chirality centers.

Question 79

A nail is an example of a chiral object.

Question 80

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