Question 1

Which of the following correctly describes the relationship between the R,S system and the +/− system associated with optically active compounds?

Accepted Answer

A)  All R enantiomers are (+). 
B)  All S enantiomers are (+). 
C)  No S enantiomers are (+), but some R enantiomers are (−). 
D)  There is no general relationship between the R,S designations and the +/− designations. 
A)  All R enantiomers are (+). 
B)  All S enantiomers are (+). 
C)  No S enantiomers are (+), but some R enantiomers are (−). 
D)  There is no general relationship between the R,S designations and the +/− designations.

Question 2

Which of the following is a representation of the enantiomer of the following substance?

Accepted Answer

A)    
B)    
C)  both a and b 
D)  neither a nor b 
A)    
B)    
C)  both a and b 
D)  neither a nor b

Question 3

How many stereocenters are present in the following triglyceride?

Accepted Answer

A)  0 
B)  1 
C)  4 
D)  6 
A)  0 
B)  1 
C)  4 
D)  6

Question 4

Which of the following molecules has an R configuration?

Accepted Answer

A)    
B)    
C)  both a and b 
D)  neither a nor b 
A)    
B)    
C)  both a and b 
D)  neither a nor b

Question 5

In which of the following are both compounds effective pain relievers?

Accepted Answer

A)  (R)-ibuprofen and (R)-naproxen 
B)  (S)-ibuprofen and (S)-naproxen 
C)  (R)-ibuprofen and (S)-naproxen 
D)  (S)-ibuprofen and (R)-naproxen 
A)  (R)-ibuprofen and (R)-naproxen 
B)  (S)-ibuprofen and (S)-naproxen 
C)  (R)-ibuprofen and (S)-naproxen 
D)  (S)-ibuprofen and (R)-naproxen

Question 6

Given the compounds 2-methyl-1-pentene and 3-methyl-1-pentene, which of the following statements is true?

Accepted Answer

A)  Only 2-methyl-1-pentene is chiral. 
B)  Only 3-methyl-1-pentene is chiral. 
C)  Both are chiral. 
D)  Neither is chiral. 
A)  Only 2-methyl-1-pentene is chiral. 
B)  Only 3-methyl-1-pentene is chiral. 
C)  Both are chiral. 
D)  Neither is chiral.

Question 7

Which of the following statements is true of levorotatory compounds?

Accepted Answer

A)  They all rotate plane polarized light in a clockwise direction. 
B)  They all rotate plane polarized light in a counterclockwise direction. 
C)  They all rotate unpolarized light in a clockwise direction. 
D)  They all rotate unpolarized light in a counterclockwise direction. 
A)  They all rotate plane polarized light in a clockwise direction. 
B)  They all rotate plane polarized light in a counterclockwise direction. 
C)  They all rotate unpolarized light in a clockwise direction. 
D)  They all rotate unpolarized light in a counterclockwise direction.

Question 8

How many stereoisomers are possible for the following compound?

Accepted Answer

A)  2 
B)  4 
C)  8 
D)  16 
A)  2 
B)  4 
C)  8 
D)  16

Question 9

How are the following two carbohydrates related to each other?

Accepted Answer

A)  enantiomers 
B)  diastereomers 
C)  constitutional isomers 
D)  They are not related to each other. 
A)  enantiomers 
B)  diastereomers 
C)  constitutional isomers 
D)  They are not related to each other.

Question 10

Which of the following is essentially biologically inactive?

Accepted Answer

A)  (R)-ibuprofen 
B)  (S)-ibuprofen 
C)  (R)-naproxen 
D)  (S)-naproxen 
A)  (R)-ibuprofen 
B)  (S)-ibuprofen 
C)  (R)-naproxen 
D)  (S)-naproxen

Question 11

Given the compounds 2-methyl-1-pentene and 2-methyl-2-pentene, which of the following statements is true?

Accepted Answer

A)  Only 2-methyl-1-pentene is chiral. 
B)  Only 2-methyl-2-pentene is chiral. 
C)  Both are chiral. 
D)  Neither is chiral. 
A)  Only 2-methyl-1-pentene is chiral. 
B)  Only 2-methyl-2-pentene is chiral. 
C)  Both are chiral. 
D)  Neither is chiral.

Question 12

Consider the following ball-and-stick model. Atoms other than carbon and hydrogen are indicated by the chemical symbol of the element.   Which of the following could also be used to specify the geometry of this substance?

Accepted Answer

A)    
B)    
C)    
D)  either a or b 
E)  a, b or c 
A)    
B)    
C)    
D)  either a or b 
E)  a, b or c

Question 13

If the specific rotation of the (R)-enantiomer of a compound is -4.8o, what will the specific rotation be for the (S)-enantiomer of the compound?

Accepted Answer

A)  +4.8° 
B)  -4.8° 
C)  0° 
D)  There is no way to tell. 
A)  +4.8° 
B)  -4.8° 
C)  0° 
D)  There is no way to tell.

Question 14

Which of the following is true of the ibuprofen-containing drugs Advil and Motrin?

Accepted Answer

A)  They are both sold as racemic mixtures. 
B)  For both only a single enantiomer is manufactured and sold. 
C)  Advil is sold as a racemic mixture but Motrin is sold as a single enantiomer. 
D)  Motrin is sold as a racemic mixture but Advil is sold as a single enantiomer. 
A)  They are both sold as racemic mixtures. 
B)  For both only a single enantiomer is manufactured and sold. 
C)  Advil is sold as a racemic mixture but Motrin is sold as a single enantiomer. 
D)  Motrin is sold as a racemic mixture but Advil is sold as a single enantiomer.

Question 15

If the specific rotation of the (R)-enantiomer of a compound is -4.8o, what will the specific rotation be for a racemic mixture of the compound?

Accepted Answer

A)  +4.8o 
B)  -4.8o 
C)  00 
D)  There is no way to tell. 
A)  +4.8o 
B)  -4.8o 
C)  00 
D)  There is no way to tell.

Question 16

Consider the following ball-and-stick model. Atoms other than carbon and hydrogen are indicated by the chemical symbol of the element.   Which carbon atom represents a stereocenter?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  None is a stereocenter. 
A)  1 
B)  2 
C)  3 
D)  4 
E)  None is a stereocenter.

Question 17

How many chiral stereoisomers are possible for 2-chlorocyclopentanol?

Accepted Answer

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

Question 18

Given the compounds 1,1-diethyl-4-methylcyclohexane, and 4-ethyl-1,1-dimethylcyclohexane, which of the following statements is true?

Accepted Answer

A)  Only 1,1-diethyl-4-methylcyclohexane is chiral. 
B)  Only 4-ethyl-1,1-dimethylcyclohexane is chiral. 
C)  Both are chiral. 
D)  Neither is chiral. 
A)  Only 1,1-diethyl-4-methylcyclohexane is chiral. 
B)  Only 4-ethyl-1,1-dimethylcyclohexane is chiral. 
C)  Both are chiral. 
D)  Neither is chiral.

Question 19

In the R,S system, which of the following groups has highest priority?

Accepted Answer

A)  alkyl 
B)  amino 
C)  hydroxyl 
D)  thiol 
A)  alkyl 
B)  amino 
C)  hydroxyl 
D)  thiol

Question 20

When the sample chamber of a polarimeter is empty which of the following statements is true?

Accepted Answer

A)  The maximum transmission of light occurs when the polarizer and analyzer are parallel to each other. 
B)  The maximum transmission of light occurs when the polarizer and analyzer are perpendicular to each other. 
C)  The maximum transmission of light occurs when the polarizer and analyzer are at an angle of 120° to each other. 
D)  Since the instrument is empty the positions of the polarizer and analyzer have no effect on the amount of transmission. 
A)  The maximum transmission of light occurs when the polarizer and analyzer are parallel to each other. 
B)  The maximum transmission of light occurs when the polarizer and analyzer are perpendicular to each other. 
C)  The maximum transmission of light occurs when the polarizer and analyzer are at an angle of 120° to each other. 
D)  Since the instrument is empty the positions of the polarizer and analyzer have no effect on the amount of transmission.

Exam 15: Chirality: the Handedness of Molecules

Which of the following correctly describes the relationship between the R,S system and the +/− system associated with optically active compounds?

Which of the following is a representation of the enantiomer of the following substance?

How many stereocenters are present in the following triglyceride?

Which of the following molecules has an R configuration?

In which of the following are both compounds effective pain relievers?

Given the compounds 2-methyl-1-pentene and 3-methyl-1-pentene, which of the following statements is true?

Which of the following statements is true of levorotatory compounds?

How many stereoisomers are possible for the following compound?

How are the following two carbohydrates related to each other?

Which of the following is essentially biologically inactive?

Given the compounds 2-methyl-1-pentene and 2-methyl-2-pentene, which of the following statements is true?

Consider the following ball-and-stick model. Atoms other than carbon and hydrogen are indicated by the chemical symbol of the element. Which of the following could also be used to specify the geometry of this substance?

If the specific rotation of the (R)-enantiomer of a compound is -4.8o, what will the specific rotation be for the (S)-enantiomer of the compound?

Which of the following is true of the ibuprofen-containing drugs Advil and Motrin?

If the specific rotation of the (R)-enantiomer of a compound is -4.8o, what will the specific rotation be for a racemic mixture of the compound?

Consider the following ball-and-stick model. Atoms other than carbon and hydrogen are indicated by the chemical symbol of the element. Which carbon atom represents a stereocenter?

How many chiral stereoisomers are possible for 2-chlorocyclopentanol?

Given the compounds 1,1-diethyl-4-methylcyclohexane, and 4-ethyl-1,1-dimethylcyclohexane, which of the following statements is true?

In the R,S system, which of the following groups has highest priority?

When the sample chamber of a polarimeter is empty which of the following statements is true?

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If the specific rotation of the (R)-enantiomer of a compound is -4.8^o, what will the specific rotation be for the (S)-enantiomer of the compound?

If the specific rotation of the (R)-enantiomer of a compound is -4.8^o, what will the specific rotation be for a racemic mixture of the compound?