Question 1

Which of the following is true of diastereomers?

Accepted Answer

A)  They possess different connectivity of atoms. 
B)  They are stereoisomers without stereocenters. 
C)  They are stereoisomers that are not mirror images. 
D)  They are stereoisomers whose mirror images are superposable. 
A)  They possess different connectivity of atoms. 
B)  They are stereoisomers without stereocenters. 
C)  They are stereoisomers that are not mirror images. 
D)  They are stereoisomers whose mirror images are superposable. C

Question 2

Progesterone, which is present in humans as a single stereoisomer, has six stereocenters. Human progesterone is one of how many possible stereoisomers for this structure?

Accepted Answer

A)  6 
B)  32 
C)  64 
D)  128 
A)  6 
B)  32 
C)  64 
D)  128 C

Question 3

Which of the following carbons is a stereocenter?

Accepted Answer

A)  a carbon that is bonded to two hydrogen atoms and two chlorine atoms 
B)  a carbonyl carbon that is bonded to a hydroxyl group and a methyl group 
C)  a carbon that is bonded to a hydrogen atom, a chlorine atom, a bromine atom, and an iodine atom 
D)  a carbonyl carbon that is bonded to a methyl group and an ethyl group 
A)  a carbon that is bonded to two hydrogen atoms and two chlorine atoms 
B)  a carbonyl carbon that is bonded to a hydroxyl group and a methyl group 
C)  a carbon that is bonded to a hydrogen atom, a chlorine atom, a bromine atom, and an iodine atom 
D)  a carbonyl carbon that is bonded to a methyl group and an ethyl group C

Question 4

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 5

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 6

Which of the following compounds can exist as a pair of enantiomers?

Accepted Answer

A)  (i) and (ii) only 
B)  (ii) and (iii) only 
C)  and (iii) only 
D)  (i) only 
A)  (i) and (ii) only 
B)  (ii) and (iii) only 
C)  and (iii) only 
D)  (i) only

Question 7

Which of the following statements is true of a hypothetical enzyme that catalyzes glyceraldehyde?

Accepted Answer

A)  It has two binding sites: one specific for -OH and the second specific for -CHO. 
B)  It has two binding sites: one specific for -COOH and the second specific for -CHO. 
C)  It has three binding sites: one specific for -H, the second specific for -COOH, and the third specific for -CHO. 
D)  It has three binding sites: one specific for -H, the second specific for -OH, and the third specific for -CHO. 
A)  It has two binding sites: one specific for -OH and the second specific for -CHO. 
B)  It has two binding sites: one specific for -COOH and the second specific for -CHO. 
C)  It has three binding sites: one specific for -H, the second specific for -COOH, and the third specific for -CHO. 
D)  It has three binding sites: one specific for -H, the second specific for -OH, and the third specific for -CHO.

Question 8

Consider the following ball-and-stick models. Elements other than hydrogen and carbon are labeled.     The specific rotation of the substance numbered one is +2.6°. If 1 g/mL of substance one is mixed with the same volume of 1 g/mL of substance two, what will be the specific rotation of the resulting solution?

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 9

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 10

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

Accepted Answer

A)  +4.8° 
B)  −4.8° 
C)  0° 
D)  +9.6° 
A)  +4.8° 
B)  −4.8° 
C)  0° 
D)  +9.6°

Question 11

Which of the following is true of the drugs Motrin (ibuprofen) and Captopril?

Accepted Answer

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

Question 12

Illustrated here are the four stereoisomers of an amino acid that 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 13

Which of the following molecules has an R configuration?

Accepted Answer

A)  ​
  
B)  ​
  
C)  both   and
  
D)  none of these 
A)  ​
  
B)  ​
  
C)  both   and
  
D)  none of these

Question 14

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 15

Which of the following is true of 2-butanol?

Accepted Answer

A)  2-butanol is superposable on its mirror image. 
B)  2-butanol and its mirror image form a pair of constitutional isomers. 
C)  2-butanol and its mirror image form diastereomers. 
D)  2-butanol is nonsuperposable on its mirror image. 
A)  2-butanol is superposable on its mirror image. 
B)  2-butanol and its mirror image form a pair of constitutional isomers. 
C)  2-butanol and its mirror image form diastereomers. 
D)  2-butanol is nonsuperposable on its mirror image.

Question 16

Which of the following molecules has an R configuration?

Accepted Answer

A)  ​
  
B)  ​
  
C)  both   and
  
D)  none of these 
A)  ​
  
B)  ​
  
C)  both   and
  
D)  none of these

Question 17

Which of the following is true of 2-butanol and 2-propanol?

Accepted Answer

A)  Both 2-butanol and 2-propanol have two stereocenters. 
B)  Both 2-butanol and 2-propanol have one stereocenter. 
C)  There are two stereocenters in 2-butanol and one stereocenter in 2-propanol. 
D)  There is one stereocenter in 2-butanol and no stereocenter in 2-propanol. 
A)  Both 2-butanol and 2-propanol have two stereocenters. 
B)  Both 2-butanol and 2-propanol have one stereocenter. 
C)  There are two stereocenters in 2-butanol and one stereocenter in 2-propanol. 
D)  There is one stereocenter in 2-butanol and no stereocenter in 2-propanol.

Question 18

Identify the type of isomerism shown by 1,2-dimethyl-cyclohexane.

Accepted Answer

A)  constitutional isomerism 
B)  enantiomerism 
C)  cis-trans isomerism 
D)  diastereomerism 
A)  constitutional isomerism 
B)  enantiomerism 
C)  cis-trans isomerism 
D)  diastereomerism

Question 19

Which of the following correctly describes the relationship between the dextrorotatory/levorotatory system and the +/− system associated with optically active compounds?

Accepted Answer

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

Question 20

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 numbered groups is assigned the highest priority?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  1 and 3 are given equal priority. 
A)  1 
B)  2 
C)  3 
D)  4 
E)  1 and 3 are given equal priority.

Exam 14: Chirality: the Handedness of Molecules

Which of the following is true of diastereomers?

Progesterone, which is present in humans as a single stereoisomer, has six stereocenters. Human progesterone is one of how many possible stereoisomers for this structure?

Which of the following carbons is a stereocenter?

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

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

Which of the following compounds can exist as a pair of enantiomers?

Which of the following statements is true of a hypothetical enzyme that catalyzes glyceraldehyde?

Which of the following is essentially biologically inactive?

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

Which of the following is true of the drugs Motrin (ibuprofen) and Captopril?

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

Which of the following molecules has an R configuration?

How many stereoisomers are possible for the following compound?

Which of the following is true of 2-butanol?

Which of the following molecules has an R configuration?

Which of the following is true of 2-butanol and 2-propanol?

Identify the type of isomerism shown by 1,2-dimethyl-cyclohexane.

Which of the following correctly describes the relationship between the dextrorotatory/levorotatory system and the +/− system associated with optically active compounds?

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 numbered groups is assigned the highest priority?

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