Question 1

Which of the following is true of a molecule which contains one stereocenter?

Accepted Answer

A)  It will never be chiral. 
B)  It will sometimes be chiral. 
C)  It will always be chiral. 
D)  There is no relationship between chirality and the presence of a stereocenter. 
A)  It will never be chiral. 
B)  It will sometimes be chiral. 
C)  It will always be chiral. 
D)  There is no relationship between chirality and the presence of a stereocenter.

Question 2

Which of the following molecules does not have an S configuration at a stereocenter?

Accepted Answer

A)    
B)    
C)    
D)  they all have an (S)-stereocenter 
A)    
B)    
C)    
D)  they all have an (S)-stereocenter

Question 3

There are six alcohols with the molecular formula C5H11OH. How many of these are chiral?

Accepted Answer

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

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

Accepted Answer

A)  aldehyde 
B)  carboxyl 
C)  ketone 
D)  primary alcohol 
A)  aldehyde 
B)  carboxyl 
C)  ketone 
D)  primary alcohol

Question 6

Which of the following is the correct order of priorities in the R,S system?

Accepted Answer

A)  aldehyde > carboxyl > ketone > primary alcohol 
B)  carboxyl > ketone > aldehyde > primary alcohol 
C)  primary alcohol > aldehyde > ketone > carboxyl 
D)  primary alcohol > ketone > carboxyl > aldehyde 
A)  aldehyde > carboxyl > ketone > primary alcohol 
B)  carboxyl > ketone > aldehyde > primary alcohol 
C)  primary alcohol > aldehyde > ketone > carboxyl 
D)  primary alcohol > ketone > carboxyl > aldehyde

Question 7

Illustrated here are the four stereoisomers of an amino acid which has two stereocenters. Which structure(s) is/are the enantiomer(s) of structure A?

Accepted Answer

A)  B only 
B)  C only 
C)  D only 
D)  C and D only 
A)  B only 
B)  C only 
C)  D only 
D)  C and D only

Question 8

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 9

What is the maximum number of stereoisomers possible for a molecule which has three stereocenters (assuming no other structural features that lead to steroisomerism)?

Accepted Answer

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

Question 10

Which of the following correctly describes the relationship between the R,S system and the actual rotation associated with optically active compounds?

Accepted Answer

A)  All R enantiomers are dextrorotatory. 
B)  All S enantiomers are dextrorotatory. 
C)  No S enantiomers are dextrorotatory, but some R enantiomers are levorotatory. 
D)  There is no general relationship between the R,S designation and the actual direction of rotation of plane polarized light. 
A)  All R enantiomers are dextrorotatory. 
B)  All S enantiomers are dextrorotatory. 
C)  No S enantiomers are dextrorotatory, but some R enantiomers are levorotatory. 
D)  There is no general relationship between the R,S designation and the actual direction of rotation of plane polarized light.

Question 11

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

Accepted Answer

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

Question 12

Which of the following is the correct order of priorities in the R,S system?

Accepted Answer

A)  tert-butyl > butyl > isopropyl > propyl 
B)  tert-butyl > isopropyl > butyl > propyl 
C)  isopropyl > tert-butyl > propyl > butyl 
D)  propyl > butyl >isopropyl > tert-butyl 
A)  tert-butyl > butyl > isopropyl > propyl 
B)  tert-butyl > isopropyl > butyl > propyl 
C)  isopropyl > tert-butyl > propyl > butyl 
D)  propyl > butyl >isopropyl > tert-butyl

Question 13

There are four alcohols with the molecular formula C4H9OH. How many of these are chiral?

Accepted Answer

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

Question 14

How many stereoisomers are possible for 3-ethyl-4-methyl-2-hexanol?

Accepted Answer

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

Question 15

Which of the three isomeric alcohols, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol, are chiral?

Accepted Answer

A)  only 2-butanol 
B)  only 2-methyl-1-propanol 
C)  both 2-butanol and 2-methyl-1-propanol 
D)  both 2-methyl-1-propanol and 2-methyl-2-propanol 
A)  only 2-butanol 
B)  only 2-methyl-1-propanol 
C)  both 2-butanol and 2-methyl-1-propanol 
D)  both 2-methyl-1-propanol and 2-methyl-2-propanol

Question 16

Which of the following pairs of stereoisomers are related as enantiomers?

Accepted Answer

A)  A and B; C and D 
B)  A and C; B and D 
C)  A and D; B and C 
D)  none of them 
A)  A and B; C and D 
B)  A and C; B and D 
C)  A and D; B and C 
D)  none of them

Question 17

Lactic acid, shown below, is produced by muscle exercise and can also be found in sour milk. Which of the following statements is true?

Accepted Answer

A)  The racemic lactic acid produced by muscle exercise is identical to that found in sour milk. 
B)  The (−)-enantiomer is produced by muscle exercise and is also found in sour milk. 
C)  The (+)-enantiomer is produced by muscle exercise and is also found in sour milk. 
D)  Lactic acid produced by muscle exercise is the (+)-enantiomer, but that found in sour milk is the (−)-enantiomer. 
A)  The racemic lactic acid produced by muscle exercise is identical to that found in sour milk. 
B)  The (−)-enantiomer is produced by muscle exercise and is also found in sour milk. 
C)  The (+)-enantiomer is produced by muscle exercise and is also found in sour milk. 
D)  Lactic acid produced by muscle exercise is the (+)-enantiomer, but that found in sour milk is the (−)-enantiomer.

Question 18

Which of the following is the correct order of priorities in the R,S system?

Accepted Answer

A)  butyl < ethyl < methyl < propyl 
B)  propyl < methyl < ethyl < butyl 
C)  butyl < propyl < ethyl < methyl 
D)  methyl < ethyl < propyl < butyl 
A)  butyl < ethyl < methyl < propyl 
B)  propyl < methyl < ethyl < butyl 
C)  butyl < propyl < ethyl < methyl 
D)  methyl < ethyl < propyl < butyl

Question 19

The sugar in deoxyribonucleic acid, DNA, is called 2-deoxy-D-ribose. It is found as a single stereoisomer. How many enantiomers of 2-deoxy-D-ribose exist?

Accepted Answer

A)  0 
B)  1 
C)  2 
D)  4 
A)  0 
B)  1 
C)  2 
D)  4

Question 20

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

Accepted Answer

A)  butyl 
B)  ethyl 
C)  methyl 
D)  propyl 
A)  butyl 
B)  ethyl 
C)  methyl 
D)  propyl

Exam 15: Chirality: the Handedness of Molecules

Which of the following is true of a molecule which contains one stereocenter?

Which of the following molecules does not have an S configuration at a stereocenter?

There are six alcohols with the molecular formula C5H11OH. How many of these are chiral?

Which of the following molecules has an R configuration?

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

Which of the following is the correct order of priorities in the R,S system?

Illustrated here are the four stereoisomers of an amino acid which has two stereocenters. Which structure(s) is/are the enantiomer(s) of structure A?

Which of the following molecules has an R configuration?

What is the maximum number of stereoisomers possible for a molecule which has three stereocenters (assuming no other structural features that lead to steroisomerism)?

Which of the following correctly describes the relationship between the R,S system and the actual rotation associated with optically active compounds?

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

Which of the following is the correct order of priorities in the R,S system?

There are four alcohols with the molecular formula C4H9OH. How many of these are chiral?

How many stereoisomers are possible for 3-ethyl-4-methyl-2-hexanol?

Which of the three isomeric alcohols, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol, are chiral?

Which of the following pairs of stereoisomers are related as enantiomers?

Lactic acid, shown below, is produced by muscle exercise and can also be found in sour milk. Which of the following statements is true?

Which of the following is the correct order of priorities in the R,S system?

The sugar in deoxyribonucleic acid, DNA, is called 2-deoxy-D-ribose. It is found as a single stereoisomer. How many enantiomers of 2-deoxy-D-ribose exist?

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

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There are six alcohols with the molecular formula C₅H₁₁OH. How many of these are chiral?

There are four alcohols with the molecular formula C₄H₉OH. How many of these are chiral?