Organic Chemistry by Janice Smith Test Bank

Chapter 1 1. Which is the most electronegative atom in the compound below? OH Br N H

A) Carbon Ans: C

B) Nitrogen

C) Oxygen

D) Bromine

2. Which of the following correctly describes the electrons of a carbon atom in its ground state? A) 3 s electrons; 3 p electrons B) 2 1s electrons; 4 2p electrons C) 2 1s electrons; 2 2s electrons; 2 2p electrons D) 2 1s electrons; 2 2s electrons; 4 2p electrons E) None of these choices is correct. Ans: C 3. Which of the following statements correctly describes the typical bonding of carbon, nitrogen, and oxygen in organic molecules? A) Carbon participates in 4 covalent bonds, oxygen participates in 2 covalent bonds and nitrogen participates in 5 covalent bonds. B) Carbon participates in 3 covalent bonds, oxygen participates in 2 covalent bonds and nitrogen participates in 5 covalent bonds. C) Carbon participates in 4 covalent bonds, oxygen participates in 3 covalent bonds and nitrogen participates in 3 covalent bonds. D) Carbon participates in 3 covalent bonds, oxygen participates in 3 covalent bonds and nitrogen participates in 5 covalent bonds. E) Carbon participates in 4 covalent bonds, oxygen participates in 2 covalent bonds and nitrogen participates in 3 covalent bonds. Ans: E 4. Which is not an acceptable Lewis structure for the anion (CH2NCO)–? a.

H C N C O H

A) a B) b Ans: C

b. H C N C O H

C) c

D) d

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c.

H

C H

N

C

d. O

H

C H

N

C

O

5. Which of the following is (are) valid Lewis structure(s) for the anion (HCONCH3) –? O H H a. C C H N H

b.

A) a B) b Ans: D

C) c

O H H C C H N H

D) d

c.

O H H C H N H

e. a, b, and c

d. a and b

E) e

6. Which of the following is (are) valid Lewis structure(s) for the anion (CH2NO2)–? Assume the atoms are arranged as drawn. a.

H O C N H O

H O C N H O

b.

A) a B) b Ans: E

C) c

c.

D) d

H O C N H O

d. a and b

e. a, b, and c

E) e

7. Which is the appropriate conversion of CH3CHClCH2CH(CH3)2 to a skeletal formula? Cl a.

c.

b.

d.

Cl

A) a B) b Ans: B

C) c

Cl

e.

Cl

D) d

E) e

8. Convert the following compound from a condensed formula to a skeletal formula: CH3CH2C(CH3)2CH2CH(CH2CH3)CH2CH(CH3)2. a.

b.

d.

e. None of the choices is correct.

A) a B) b Ans: D

C) c

D) d

c.

E) e

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C

9. What is the condensed formula of the compound below? Br Br a. CH3CH2CH(CH3)CH2CH(CH3)CHBr2 b. CH3CH2CH2(CH3)CH2CH(CH3)CHBr2 c. CH3CH2CH(CH3)CH(CH3)CH2CHBr2

A) a B) b Ans: A

C) c

10. Convert the following skeletal formula to a condensed formula.

a. CH3CH2CH(CH3)2CH(CH2CH3)CH(CH3)2 b. CH3CH2CH(CH3)CH(CH2CH3)CH(CH3)2 c. CH3CH(CH3)CH(CH2CH3)CH(CH3)2

A) a B) b Ans: B

C) c

11. Which of the following is not a valid Lewis structure of CH3NO2? H H a.

H

N O

H H O

A) a B) b Ans: B

b.

C) c

H

N O

H H

H H O

D) d

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c. H

N O

O

d.

2

H

N O

O

12. Which is not a valid resonance structure for the anion below? O H2C

CH3 O

a.

H2C

O

O

CH3

b.

CH3

e. All are valid resonance structures.

CH3

H2C

c.

H2C

CH3

O d.

H2C

A) a B) b Ans: C

C) c

D) d

E) e

13. How are the molecules in the following pair related? H3C

O

CH2

and

O

H3C

CH2

A) They are constitutional isomers. B) They are resonance structures. Ans: B

C)

They represent the same structure.

14. How are the molecules in the following pair related? and

H3C C CH

A) They are constitutional isomers. B) They are resonance structures. Ans: A

C)

Neither of the choices is correct.

15. How are the molecules in the following pair related? O

Cl

O and Cl

A) They are constitutional isomers. B) They are resonance structures. Ans: A

C)

Neither of the choices is correct.

16. How are the molecules in the following pair related? and

A) They are constitutional isomers. B) They are resonance structures. Ans: C

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C)

They are unrelated molecules.

17. How are the molecules in the following pair related?

H3C

O N

O N

and H3C

O

O

A) They are constitutional isomers. B) They are resonance structures. Ans: B

C)

Neither of the choices is correct.

18. How are the molecules in the following pair related? and

A) They are constitutional isomers. B) They are resonance structures. Ans: A

C)

Neither of the choices is correct.

19. How are the molecules in the following pair related? and

A) They are constitutional isomers. B) They are resonance structures. Ans: B

C)

Neither of the choices is correct.

20. How are the molecules in the following pair related? NH

OH and

H3C

CH3

H3C

NH

A) They are constitutional isomers. B) They are resonance structures. Ans: C

C)

They are unrelated molecules.

21. How are the molecules in the following pair related? O and H3C

OH

CH3

A) They are constitutional isomers. B) They are resonance structures. Ans: A

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C)

Neither of the choices is correct.

22. Which is the most accurate representation of the resonance hybrid for the resonance structures shown below? O

a. δ−

O

O

δ− O δ−

δ− O δ−

b.

δ−

δ− O δ−

c.

O

δ− δ−

d. δ−

e. None of the choices is correct.

A) a B) b Ans: B

C) c

D) d

E) e

23. Which of the following pairs of compounds are resonance structures? O and H3 C

CH3

H3 C

CH3

CH3 c.

OH

b.

and

a.

and

A) a B) b Ans: B

C) c

24. Which of the following structures are resonance structures of each other? a.

A) B) C) D) E) Ans:

b.

c.

a and b b and c a and c All are resonance structures. None of these are resonance structures. A

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CH2

δ−

25. What is the hybridization for each of the indicated atoms in the following compound? N

H2 C

b

a

CH3

c

A) a - sp2; b - sp2; c - sp2 B) a - sp2; b - sp3; c - sp3 Ans: D

C) D)

a - sp; b - sp2; c - sp3 a - sp2; b - sp2; c - sp3

26. Indicate the hybridization of the carbon ion in each compound below. CH3

CH3 a.

b.

A) a - sp2; b - sp2 Ans: D

B) a - sp2; b - sp3

C) a - sp3; b - sp3

D) a - sp3; b - sp2

27. Consider the organic molecule drawn below. Describe which orbitals are used to form the C=O bond. Since there are two bonds, you must identify two different sets of orbitals. O

A) B) C) Ans:

O H Csp2 – Osp2 and Cs– Op Csp – Osp and Cp – Op Csp2 – Osp2 and Cs – Os E

D) E)

Csp3 – Osp2 and Cp– Op Csp2 – Osp2 and C2p – O2p

28. Which of the following compounds has a labeled carbon atom that is sp2 hybridized? CH3

NH a.

b.

H2C C CH2

d. Compounds b and c

A) a B) b Ans: D

C) c

H3C

CH3

c.

H3C

CH3

e. a, b and c all have sp3 hybridized carbon.

D) d

E) e

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29. Which of the following compounds contains a labeled atom that is sp hybridized? (All nonbonded electron pairs have been drawn in.) a.

b.

C O

A) a B) b Ans: D

HC N

C) c

c.

D) d

O C H

d. a and b

e. a, b and c

E) e

30. Which of the compounds drawn below contains an sp2 hybridized carbon atom? Select any and all structures that apply. a. CO2

A) a only Ans: E

c. CH3+

b. H2C O

B) b only

C) d only

d. CH3OH

D) a and b

E) b and c

31. Which of the labeled carbon atoms is (are) sp2 hybridized? O a.

A) a B) b Ans: D

b. CH3+

C) c

c. H2C C CH2

D) d

d. a and b

e. a, b and c

E) e

32. Which statement best describes the orbital hybridization used to form bonds in the cation below? H2C C N

The σ bond between the two carbon atoms is formed between two sp2 hybridized atoms. B) The σ bond between the C and N is formed between an sp2 hybridized C and an sp hybridized N. C) The σ bond between the two carbons is formed between one sp3 hybridized C and one sp hybridized C. D) The lone pair of electrons on N is in an sp hybridized orbital. E) None of the statements is correct. Ans: D A)

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33. Indicate the formal charge on the B, O, and F atoms in the following compound. Cl Cl B F O

A) B) C) Ans:

B: +1; O: +1; F: 0 B: –1; O: –1; F: 0 B: +1; O: –1; F: 0 D

D) E)

B: –1; O: +1; F: 0 None of the choices is correct.

34. In the following compound, indicate the formal charge on all atoms except hydrogen.

H

O C

A) B) C) Ans:

N

Carbon +1; Oxygen +1; Nitrogen –2 D) Carbon –1; Oxygen +1; Nitrogen –2 E) Carbon +1; Oxygen –1; Nitrogen –2 C

Carbon +1; Oxygen –1; Nitrogen –1 None of the choices is correct.

35. In the following compound, indicate the formal charge on all atoms except hydrogen, from left to right. H H C N C O H

A) B) C) D) E) Ans:

Carbon 0; Nitrogen –1; Carbon +1; Oxygen 0 Carbon –0; Nitrogen –1; Carbon 0; Oxygen –1 Carbon 0; Nitrogen –1; Carbon 0; Oxygen –1 Carbon 0; Nitrogen +1; Carbon 0; Oxygen –1 None of the choices is correct. D

36. Which of the following compounds has a labeled atom with a +1 formal charge? (All nonbonded electron pairs have been drawn in.)

a.

H2C

N

N

A) a B) b Ans: C

b.

H

C) c

C

CH2

c. H

D) d

E) e

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C

CH2

d.

H C H

e. H

H N

O H

H

37. Which of the following species has a labeled atom with a +1 formal charge? (All nonbonded electron pairs have been drawn in.) H a.

H N H

b.

A) a B) b Ans: A

H N

C) c

d. H3C C CH3

c. H2C O

H

D) d

e.

E) e

38. Which of the following species contains a carbon atom with a +1 formal charge? (All nonbonded electron pairs have been drawn in.) a.

H

H C

H C H H

b.

A) a B) b Ans: A

C

H

H

C H

C) c

c.

D) d

H C C

d.

H CH3 C N H CH3

e.

H

H C

H C H H

E) e

39. Which of the following species contains a carbon atom with a –1 formal charge? (All nonbonded electron pairs have been drawn in.)

a.

H C C H

b.

A) a B) b Ans: B

H

H C

C) c

C

c.

H

D) d

d.

H C H

H

H C

e. H2C C CH2

H

E) e

40. Which of the following species contains an O atom with a +1 formal charge? (All nonbonded electron pairs have been drawn in.) OH a.

O

O

b.

c.

d.

O

A) a B) b Ans: B

C) c

D) d

e.

O

N

O

E) e

41. Which of the following species contains a carbon atom with a +1 formal charge? (All nonbonded electrons and electron pairs have been drawn in.) a. H C C

A) a B) b Ans: D

b.

H CH3 C N H CH3

C) c

D) d

c.

H

H C

CH3

C H OH

E) e

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d.

CH2

e.

H

C

C H

H

42. Which of the following species has (have) a trigonal planar structure with 120° bond angles around the labeled carbon atom? NH a. H2C C CH2

b.

A) a B) b Ans: D

C) c

H3C

CH3 c.

CH3

D) d

H3C

CH3

d. b and c

e. a, b and c

E) e

43. Which of the following molecules has (have) a trigonal planar geometry? O a.

b.

A) a B) b Ans: A

O

c.

C) c

D) d

H N

d. a and c

e. None of the choices are correc

E) e

44. Which of the following compounds possess(es) a nitrogen with tetrahedral geometry? A) CH3C N: B) NH2– C) NH4+ D) CH3C N: and NH2– are both tetrahedral. E) NH2– and NH4+ are both tetrahedral. Ans: E 45. Which of the following molecules is (are) polar? a. CH3Cl

A) a B) b Ans: D

b. CH2Cl2

C) c

c. CCl4

D) a and b

E) b and c

46. Which of the following statements is (are) correct? A) Ethane has sp3 carbon atoms and the geometry around each carbon is trigonal planar. B) Ethane has sp3 carbon atoms and the geometry around each carbon is tetrahedral. C) Ethane has sp2 carbon atoms and the geometry around each carbon is tetrahedral. D) Ethane has sp2 carbon atoms and the geometry around each carbon is trigonal planar. E) None of the statements are correct. Ans: B

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47. Which of the following statements is (are) correct? A) The carbon–carbon distance in acetylene is longer than in ethylene. B) The carbon–hydrogen bond in acetylene is weaker than the carbon–hydrogen bond in ethane. C) The carbon–carbon distance in acetylene is shorter than in ethane. D) The statements (The carbon–carbon distance in acetylene is longer than in ethylene) and (The carbon hydrogen bond in acetylene is weaker than the carbon hydrogen bond in ethane) are correct. E) The statements (The carbon hydrogen bond in acetylene is weaker than the carbon hydrogen bond in ethane) and (The carbon–carbon distance in acetylene is shorter than in ethane) are correct. Ans: C 48. How many hydrogens are directly bonded to each of the indicated carbon atoms? Cc

Ca

Cb

A) B) C) Ans:

Ca 1; Cb 3; Cc 2 Ca 2; Cb 3; Cc 2 Ca 1; Cb 2; Cc 2 A

D) E)

Ca 1; Cb 3; Cc 3 None of the choices is correct.

49. Of the molecules listed, which does not have a dipole moment? A) HCl B) NCl3 C) CO D) BF3 E) All molecules have a dipole moment. Ans: D 50. For the elements Rb, F, and O, the order of increasing electronegativity is: A) Rb < F < O D) F < Rb < O B) Rb < O < F E) The order cannot be determined. C) O < F < Rb Ans: B 51. Which of the following Lewis dot structure(s) below bear(s) a positive charge? a.

H

Be H

H b. H B H H

A) a B) b Ans: E

C) c

c. H N H H

D) c and d

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d.

H H N H H

E) d and e

e.

O

52. Which of the following species has (have) a trigonal planar structure? a.

CH3

A) B) C) Ans:

b.

CH3

c.

d.

NH3

a, b, and c b and d d B

D) E)

BF3

e.

OH3

b, d, and e All of the choices are correct.

53. What is the molecular shape of methyl anion? CH3

A) B) C) Ans:

Octahedral Tetrahedral Trigonal planar D

D) E)

Trigonal pyramidal Linear

Challenge Questions 54. Enalapril is currently in clinical trials for congestive heart failure, and its structure is given below. What is the correct molecular formula for this interesting antihypertensive agent? OH O O

N

HN O O

a. C20H28N2O5

d. C20H26N2O5

b. C18H26N2O5

e. C18H25N2O5

c. C16H24N2O5

Enalapril

A) a B) b Ans: A

C) c

D) d

E) e

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55. The following compound is a synthetic intermediate in the production of lactacystin. Identify the orbital hybridization and geometry of the atoms next to the three arrows. a O

O N Si

CN O

b

c

a – sp3; b – sp2; c – sp3 a – sp2; b – sp; c – sp3 a – sp2; b – sp3; c – sp2 D

A) B) C) Ans:

D) E)

a – sp3; b – sp2; c – sp None of the choices is correct.

56. The following scheme represents an SN1 mechanism for the conversion of alkyl halide “a” to ether “b.” Determine the correct structure for intermediate “X” based on the curved arrow formulism shown. H

I OH

H + I

OH

O OH

OH X b

a

H O

OH

a.

A) a B) b Ans: C

b.

C) c

c.

D) d

E) e

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H

d.

H O H

e.

57. With reference to compound X drawn below, label each compound as an isomer, a resonance structure or neither. O N H

N H

X

A) B) C) D) E) Ans:

H N

O

a.

O N H

O b.

O

c.

NH2 d.

a. resonance structure; b. isomer; c. neither; d. isomer a. isomer; b. resonance structure; c. isomer; d. neither a. isomer; b. neither; c. isomer; d. resonance structure a. resonance structure; b. isomer; c. resonance structure; d. isomer None of the choices are correct. D

Use the following to answer questions 58-60: Answer the following questions about lidocaine, a commonly used dental anesthetic. a

H N

N O

Lidocaine

c

58. What orbitals are used to form the bond indicated by a? A) Csp2―Csp2 B) Csp3―Csp2 C) Csp2―Csp Csp3―Csp Ans: B

D) Csp―Csp2

59. How many carbon atoms have sp2 hybridization? A) 7 B) 5 C) 6 D) 10 E) 8 Ans: A 60. Predict the geometry around the oxygen atom indicated by arrow c. A) Linear D) Trigonal planar B) Tetrahedral E) Square planar C) Trigonal bipyrimidal Ans: D

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E)