Question 1

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)  C and D; B and C 
A)  A and B; C and D 
B)  A and C; B and D 
C)  A and D; B and C 
D)  C and D; B and C

Question 2

Which of the three isomeric alcohols, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol, is/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 3

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 4

Why is 4-ethyl-1,1-dimethylcyclohexane achiral?

Accepted Answer

A)  because it has nonsuperimposable mirror images 
B)  because it has more than one stereocenter 
C)  because all ring carbon atoms are bonded to two identical groups 
D)  because all ring carbon atoms are bonded to four different groups 
A)  because it has nonsuperimposable mirror images 
B)  because it has more than one stereocenter 
C)  because all ring carbon atoms are bonded to two identical groups 
D)  because all ring carbon atoms are bonded to four different groups

Question 5

Among the following groups, what is the correct order of priorities in the R,S system?

Accepted Answer

A)  (i) > (ii) > (iii) > (iv) 
B)  (ii) > (i) > (iv) > (iii) 
C)  (iv) > (ii) > (i) > (iii) 
D)  (ii) > (iv) > (i) > (iii) 
A)  (i) > (ii) > (iii) > (iv) 
B)  (ii) > (i) > (iv) > (iii) 
C)  (iv) > (ii) > (i) > (iii) 
D)  (ii) > (iv) > (i) > (iii)

Question 6

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 7

Chymotrypsin has 251 stereocenters. What is the maximum number of stereoisomers possible for a molecule with this number of stereocenters?

Accepted Answer

A)  251 
B)  2 × 251 
C)  2251 
D)  10251 
A)  251 
B)  2 × 251 
C)  2251 
D)  10251

Question 8

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 9

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 10

Which of the following three isomeric alcohols, 2-pentanol, 2-methyl-2-butanol, and 3-methyl-2-butanol, is/are chiral?

Accepted Answer

A)  only 2-pentanol 
B)  only 2-methyl-2-butanol 
C)  both 2-pentanol and 2-methyl-2-butanol 
D)  both 2-pentanol and 3-methyl-2-butanol 
A)  only 2-pentanol 
B)  only 2-methyl-2-butanol 
C)  both 2-pentanol and 2-methyl-2-butanol 
D)  both 2-pentanol and 3-methyl-2-butanol

Question 11

The drugs Prilosec and Nexium both contain the same active ingredient. Nexium contains a single enantiomer, but Prilosec is a racemic mixture. Which of the following is probably true regarding 20 mg doses of the two different drugs?

Accepted Answer

A)  Both drugs will be equally effective. 
B)  Both drugs can be prepared using the same synthetic procedure. 
C)  Nexium will be more effective than Prilosec. 
D)  Prilosec will be more effective than Nexium. 
A)  Both drugs will be equally effective. 
B)  Both drugs can be prepared using the same synthetic procedure. 
C)  Nexium will be more effective than Prilosec. 
D)  Prilosec will be more effective than Nexium.

Question 12

Among the following groups, which is the correct order of priorities in the R,S system?

Accepted Answer

A)  (ii) > (i) > (iii) > (iv) 
B)  (iii) > (iv) > (ii) > (i) 
C)  (i) > (iii) > (ii) > (iv) 
D)  (iv) > (iii) > (i) > (ii) 
A)  (ii) > (i) > (iii) > (iv) 
B)  (iii) > (iv) > (ii) > (i) 
C)  (i) > (iii) > (ii) > (iv) 
D)  (iv) > (iii) > (i) > (ii)

Question 13

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 14

How many stereoisomers are possible for the following triglyceride? (Include all types of stereoisomerism!)

Accepted Answer

A)  1 
B)  2 
C)  4 
D)  8 
A)  1 
B)  2 
C)  4 
D)  8

Question 15

How many stereoisomers exist for the following compound?

Accepted Answer

A)  1 
B)  2 
C)  4 
D)  8 
A)  1 
B)  2 
C)  4 
D)  8

Question 16

Given the compounds cis-1,4-dimethylcyclohexane and trans-1,4-dimethylcyclohexane, which of the following statements is/are true? (i) these two compounds are related to each other as stereoisomers;
(ii) cis-1,4-dimethylcyclohexane is chiral;
(iii) trans-1,4-dimethylcyclohexane is chiral.

Accepted Answer

A)  Only (i) is true. 
B)  Only (i) and (ii) are true. 
C)  Only (ii) and (iii) are true. 
D)  Only (i) and (iii) are true. 
A)  Only (i) is true. 
B)  Only (i) and (ii) are true. 
C)  Only (ii) and (iii) are true. 
D)  Only (i) and (iii) are true.

Question 17

Consider the following ball-and-stick model. Elements other than hydrogen and carbon are labeled.     If the specific rotation of this substance is +2.6°, then what is the specific rotation of the following substance?

Accepted Answer

A)  +2.6° 
B)  −2.6° 
C)  0° 
D)  +5.2° 
E)  −5.2° 
A)  +2.6° 
B)  −2.6° 
C)  0° 
D)  +5.2° 
E)  −5.2°

Question 18

What are the R/S configurations at the stereocenters of the following compounds?

Accepted Answer

A)  (i) R; (ii) R 
B)  (i) R; (ii) S 
C)  (i) S; (ii) R 
D)  (i) S; (ii) S 
A)  (i) R; (ii) R 
B)  (i) R; (ii) S 
C)  (i) S; (ii) R 
D)  (i) S; (ii) S

Question 19

Which of the following would represent a racemic mixture?

Accepted Answer

A)  a 1:1 mixture of 1-butanol and 2-butanol 
B)    
C)    
D)  all of these 
A)  a 1:1 mixture of 1-butanol and 2-butanol 
B)    
C)    
D)  all of these

Question 20

Given the compounds 2,3-dimethylpentane and 3-methylhexane, which of the following is true?

Accepted Answer

A)  Only 2,3-dimethylpentane is chiral. 
B)  Only 3-methylhexane is chiral. 
C)  Both are chiral. 
D)  Neither is chiral. 
A)  Only 2,3-dimethylpentane is chiral. 
B)  Only 3-methylhexane is chiral. 
C)  Both are chiral. 
D)  Neither is chiral.

Exam 14: Chirality: the Handedness of Molecules

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

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

Which of the following statements is true of levorotatory compounds?

Why is 4-ethyl-1,1-dimethylcyclohexane achiral?

Among the following groups, what is the correct order of priorities in the R,S system?

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

Chymotrypsin has 251 stereocenters. What is the maximum number of stereoisomers possible for a molecule with this number of stereocenters?

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

How many stereocenters are present in the following triglyceride?

Which of the following three isomeric alcohols, 2-pentanol, 2-methyl-2-butanol, and 3-methyl-2-butanol, is/are chiral?

The drugs Prilosec and Nexium both contain the same active ingredient. Nexium contains a single enantiomer, but Prilosec is a racemic mixture. Which of the following is probably true regarding 20 mg doses of the two different drugs?

Among the following groups, which is the correct order of priorities in the R,S system?

How many chiral stereoisomers are possible for 2-chlorocyclopentanol?

How many stereoisomers are possible for the following triglyceride? (Include all types of stereoisomerism!)

How many stereoisomers exist for the following compound?

Given the compounds cis-1,4-dimethylcyclohexane and trans-1,4-dimethylcyclohexane, which of the following statements is/are true? (i) these two compounds are related to each other as stereoisomers; (ii) cis-1,4-dimethylcyclohexane is chiral; (iii) trans-1,4-dimethylcyclohexane is chiral.

Consider the following ball-and-stick model. Elements other than hydrogen and carbon are labeled. If the specific rotation of this substance is +2.6°, then what is the specific rotation of the following substance?

What are the R/S configurations at the stereocenters of the following compounds?

Which of the following would represent a racemic mixture?

Given the compounds 2,3-dimethylpentane and 3-methylhexane, which of the following is true?

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