Organic Chemistry Answers

16. A mixture of equal amounts of two enantiomers __________.

A) Is called a racemic mixture

B) Is optically inactive

C) Implies that the enantiomers are meso forms

D) Both A and B

E) None of the above

17. Which of the following is chiral?

A) cis-1-bromo-3-chlorocyclobutane

B) cis-1, 4-dimethylcyclohexane

C) trans-1, 3-dimethylcyclohexane

D) trans-1-bromo-3-chlorocyclobutane

E) cis-1, 3-dimethylcyclohexane

20. Which of the statements below correctly describes an achiral molecule?

A) The molecule might be a meso form.

B) The molecule has a nonsuperimposable mirror image.

C) The molecule exhibits optical activity when it interacts with plane-polarized light.

D) The molecule has an enantiomer.

E) None of the above.

12. Which structure(s) represent(s) diastereomer(s) of I?

A) II

B) II and III

C) II and IV

D) III and V

13. (2R, 4S) –2, 4–Dichloropentane and (2S, 4R)-2, 4-dichloropentane are:

A) Enantiomers

B) Diastereomers

C) Identical

D) Constitutional isomers

15. Which of the following is/are optically inactive?

A) Every achiral compound

B) A racemic mixture

C) A meso compound

D) A 50-50 mixture of R and S enantiomers

E) All the above

Which compound would show optical activity?

A) cis 1, 4- dimethylcyclohexane

B) trans 1, 4- dimethylcyclohexane

C) cis 1,4- dimethylcycloheptane

D) trans 1, 4- dimethylcycloheptane

10. What can be said with certainty if a compound has [α] D = -9.25°?

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A) The compound has the (S) configuration.

B) The compound has the (R) configuration.

C) The compound is not a meso form.

D) The compound possesses only one stereogenic center.

11. The molecules shown are:

A) Constitutional isomers.

B) Enantiomers.

C) Diastereomers.

D) Identical.   

Use the following to answer questions 5-8:

Consider the following compounds

5. Which of the compounds above (I-IV) represent enantiomers?

A) I and II

B) II and III

C) III and IV

D) II and IV

6. Which compound above (I-IV) is a meso compound?

A) I

B) II

C) III

D) IV

7. Which compound above (I-IV) is (2R, 3R)-2, 3-butanediol?

A) I

B) II

C) III

D) IV

8. Which compounds above (I-IV) form a set of stereoisomers?

A) I, II and III

B) II, III and IV

C) II and III

D) I, III and IV

E) I, II, III and IV

1. Which of the following is the pair of enantiomer from the following substance?

A) I and II

B) II and III

C) III and IV

D) I and V

4. How many stereogenic centers are there in Lovastatin ( Mevacor® : a cholesterol lowering drug) ?

  A) 8

  B) 5

  C) 6

  D) 7

1. Which of the following statements regarding enantiomers is not true?

A) All (+) enantiomers are levorotatory

B) All (-) enantiomers rotate plane polarized light in a counterclockwise direction

C) (+) and (-) enantiomers rotate plane polarized light in opposite directions

D) All R enantiomers are dextrorotatory

1. Which of the following is/are the S-enantiomer of alanine?

      A) Only 1

      B) Only 2

      C) 1 and 3

       D) 2 and 3