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Introduction


Definitions


Three-Dimensional Representations


Assigning Priorities


Determining Stereochemical Relationships


Question Sets


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Definitions: Testing Your Knowledge


Choose the correct answer for each of the following 15 multiple choice questions relating to the Definitions section of this tutorial. Don't look back at the previous pages for the answers; instead, work out the answers based on what you remember. Then click Submit to check your answers and see explanations for the correct choices.

1. Constitutional isomers are molecules that have
a. different molecular formulas, connectivities, and spatial orientations.
b. the same molecular formulas and different connectivities.
c. the same molecular formulas, connectivities, and spatial orientations.
d. a non-superimposable mirror image.

2. What is the difference between conformational isomers and configurational isomers?
a. Conformational isomers are not stereoisomers, and configurational isomers are stereoisomers.
b. Conformational isomers cannot be converted into one another by rotation around a single bond, and configurational isomers can be converted into one another by rotation around a single bond.
c. Conformational isomers can be converted into one another by rotation around a single bond, and configurational isomers cannot be converted into one another by rotation around a single bond.
d. Conformational isomers are stereoisomers, and configurational isomers are not stereoisomers.

3. A molecule that has does not have a plane or center of symmetry is
a. achiral.
b. chiral.
c. prochiral.
d. an enantiomer.

4. A mixture with an enantiomeric excess of 40% R has what compositition of enantiomers?
a. 40% R and 60% S.
b. 40% S and 60% R.
c. 70% S and 30% R.
d. 70% R and 30% S.

5. A chiral molecule with five stereocenters has how many different forms?
a. Five (5).
b. Ten (10).
c. Sixteen (16).
d. Thirty-two (32).

6. An achiral molecule typically has
a. a center of symmetry.
b. a plane of symmetry.
c. either of the above.
d. none of the above.

7. What can be said about the following molecule?


a. It is chiral.
b. It is prochiral.
c. It is achiral.
d. It has seven different forms.

8. What is the best way to describe the relationship between the following two molecules?


a. They are isomers.
b. They are stereoisomers.
c. They are geometric isomers.
d. They are optical isomers.

9. What is the best way to describe the relationship between the following two molecules?


a. They are enantiomers.
b. They are diastereomers.
c. They are identical.
d. They are conformational isomers.

10. Choose the molecule(s) below that is a (are) diastereomer(s) of the following molecule.


a.
b.
c.
d. Both a and c.

11. What is the best way to describe the relationship between the following two molecules?


a. They are isomers.
b. They are constitutional isomers.
c. They are stereoisomers.
d. They have no relationship.

12. How many chiral and prochiral atoms does the following molecule have?


a. Five (5) chiral atoms and four (4) prochiral atoms.
b. Five (5) chiral atoms and six (6) prochiral atoms.
c. Six (6) chiral atoms and eleven (11) prochiral atoms.
d. Five (5) chiral atoms and eleven (11) prochiral atoms.

13. Will an equal mixture of the following two molecules cause a net rotation of plane-polarized light? (Assume that the molecule on the right will rotate light.)


a. Yes.
b. No.
c. This cannot be determined with the information given.

14. Will an equal mixture of the following two molecules cause a net rotation of plane-polarized light? (Assume that the molecule on the right will rotate light.)


a. Yes.
b. No.
c. This cannot be determined with the information given.

15. Will an equal mixture of the following two molecules cause a net rotation of plane-polarized light? (Assume that the molecule on the right will rotate light.)


a. Yes.
b. No.
c. This cannot be determined by the information given.




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