64 Practice Problems – Chapter 14 – Chem 1C
1. Which of the following molecules contains a nitrogen atom that is sp2 hybridized?
A) NH3
B) NO3-
C) N2
D) HCN
E) C2N2
2. Consider the structure of glycine, the simplest amino acid: What is the total number of  bonds in the molecule?
A) 0
B) 1/2
C) 1
D) 2
E) More information is needed.
3. What is the hybridization of I in the molecule ICl3?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
4. What is the hybridization of S in the molecule H2S?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
5. What is the hybridization of C in the ion CN-?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
6. Atoms that are sp3 hybridized form ____ pi bond(s).
A) 0
B) 1
C) 2
D) 3
E) 4
7. What is the hybridization of the central atom in SF6?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3

8. What is the hybridization of the central atom in PCl4+?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
9. What is the hybridization of the central atom in IF5?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
10. What is the hybridization of the central atom in SF4?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
11. What is the hybridization of O in OF2?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
12. Consider the following molecule. (Lone pairs are not drawn in.) Specify the hybridization of each carbon atom (in numeric order: C-1 C-2 C-3 C-4 C-5).
A) sp2 sp2 sp2 sp3 sp
B) sp2 sp2 sp2 sp3 sp3
C) sp2 sp2 sp3 sp3 sp
D) sp2 ssp2 sp3 sp3 sp3
E) sp sp sp sp2 sp
13. What is the hybridization of the phosphorus atom in PF4+?
A) dsp2
B) sp2
C) d2sp3
D) sp2d
E) sp3
14. What is the hybridization of the central I atom in the molecule ICl5?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3

15. Which of the following has a central atom that is dsp3 hybridized?
A) SF4–
B) PF5
C) CF4
D) SCl6
E) SO2
16. What is the hybridization of the S atom in the molecule SO3?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
17. What is the hybridization of the I atom in the ion IF4-?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3

Use the following to answer questions 18-21:

Consider the following molecule. (Lone pairs are not drawn in.)

18. What is the hybridization of the carbon atom that is double-bonded to oxygen?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
19. What is the hybridization of the carbon atom that is bonded to chlorine?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
20. What is the hybridization of the nitrogen atom?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
21. What is the hybridization of the oxygen atom?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3

22. Which of the following has two  bonds?
A) C2H6
B) C2H4
C) C2H2
D) at least two of these
E) none of these
23. Consider the following Lewis structure. (Lone pairs are not drawn in.) Which statement about the molecule is false?
A) There are 10 sigma and 2 pi bonds.
B) C-2 is sp2 hybridized with bond angles of 120.
C) Oxygen is sp3 hybridized.
D) This molecule contains 28 valence electrons.
E) There are some H–C–H bond angles of about 109 in the molecule.

Use the following to answer questions 24-26:

Tetracyanoethylene has the skeleton shown here: From its Lewis structure, determine the following.

24. How many sigma bonds and how many pi bonds are in the molecule?
A) 5 sigma and 9 pi
B) 6 sigma and 8 pi
C) 9 sigma and 7 pi
D) 9 sigma and 9 pi
E) 5 sigma and 8 pi
25. How many of the atoms are sp2 hybridized?
A) 2
B) 4
C) 6
D) 8
E) 10
26. How many of the atoms are sp hybridized?
A) 2
B) 4
C) 6
D) 8
E) 10

27. Which statement about N2 is false?
A) It is a gas at room temperature.
B) The oxidation state is +3 on one N and –3 on the other.
C) It has one sigma bond and two pi bonds between the two atoms.
D) It can combine with H2 to form NH3.
E) It has two pairs of nonbonding electrons.

28. Consider the structure of glycine, the simplest amino acid: What is the total number of bonds in the molecule?
A) 6
B) 7
C) 8
D) 10
E) 11
29. Which of the following has the shortest N-O bond?
A) NO3–
B) NO+
C) N2
D) NO2–
E) none of these
30. Specify the hybridization of the nitrogen atom in each of the following, in order. NO3– N2 NO2–
A) sp3, sp, sp
B) sp2, sp, sp2
C) sp2, sp, sp3
D) sp3, sp2, sp3
E) none of these
31. In which of the compounds below is there more than one kind of hybridization (sp, sp2, sp3) for carbon? I. CH3CH2CH2CH3 II. CH3CH = CHCH3 III. CH2 = CH – CH = CH2 IV. H – CC – H
A) II and III
B) II only
C) III and IV
D) I and IV
E) III only
32. The CCH bond angles in ethylene, C2H4, are 120. What is the hybridization of the carbon orbitals?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
33. Consider the structure of glycine, the simplest amino acid: Indicate the hybridizations at each N and C atom in the molecule (in sequence from left to right).
A) sp3 sp3 sp2
B) sp3 sp3 sp3
C) sp2 sp2 sp2
D) sp2 sp3 sp2
E) none of these

34. Complete the Lewis structure for the following molecule. This molecule has __________ sigma bonds and __________ pi bonds.
A) 4, 5
B) 6, 3
C) 11, 5
D) 13, 2
E) 13, 3
35. Describing the bonding in C2H4 requires what carbon hybridization?
A) sp3
B) sp2
C) sp
D) d2sp3
E) dsp2
36. Consider the following Lewis structure. (Lone pairs are not drawn in.) What are the hybridizations of the oxygen atom and of carbon atoms 1, 2, and 4, respectively (order: O C-1 C-2 C-4)?
A) sp3 sp3 sp sp2
B) sp sp3 sp sp
C) sp sp2 sp sp2
D) sp2 sp3 sp2 sp3
E) sp sp3 sp2 sp
37. What is the hybridization of each N atom in the molecule N2H4?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
38. Which statement about the thiocyanate ion, SCN–, is true?
A) Its Lewis structure contains an unpaired electron.
B) Its shape is bent like that of H2O.
C) Only one correct resonance structure can be drawn.
D) There are more than two  bonds in the ion.
E) none of these
39. Which of the following statements is correct?
A) A triple bond is composed of two  bonds and one  bond.
B)  bonds result from the head-to-head overlap of atomic orbitals.
C) Free rotation may occur about a double bond.
D)  bonds have electron density on the internuclear axis.
E) More than one of these statements are correct.
40. As the bond order of a bond increases, its bond energy ______ and its bond length ______.
A) increases, increases
B) decreases, decreases
C) increases, decreases
D) decreases, increases

41. If four orbitals on one atom overlap four orbitals on a second atom, how many molecular orbitals will form?
A) 1
B) 4
C) 8
D) 16
E) none of these
42. For which of the following diatomic molecules would the bond order become greater if an electron were removed, that is, if the molecule were converted to the positive ion in its ground state?
A) B2
B) C2
C) P2
D) F2
E) Na2
43. The configuration (2s)2(2s*)2(2py)1(2px)1 is the molecular orbital description for the ground state of which of the following species?
A) Li2+
B) Be2
C) B2
D) B22–
E) C2
44. Which of the following species has the largest dissociation energy?
A) O2
B) O2–
C) O22–
D) O2+
E) O22+
45. Which of the following is paramagnetic?
A) B2
B) C2
C) H2
D) N2
E) F2
46. Order the following from shortest to longest bond: C2, B2, H2, N2
A) H2, N2, C2, B2
B) N2, C2, B2, H2
C) C2, N2, H2, B2
D) C2, B2, H2, N2
E) none of these
47. Which charge(s) of O2 would give a bond order of 3?
A) +1
B) -2
C) +2
D) -1
E) +3
48. Which of the following statements is false?
A) C2 is paramagnetic.
B) C2 is diamagnetic.
C) The carbon-carbon bond in C22– is stronger than the one in CH3CH3.
D) The carbon-carbon bond in C22– is shorter than the one in CH3CH3.
E) Two of these statements are false.
49. Which of the following statements is true?
A) Electrons are never found in an antibonding MO.
B) All antibonding MOs are higher in energy than the atomic orbitals of which they are composed.
C) Antibonding MOs have electron density mainly outside the space between the two nuclei.
D) None of these statements is true.
E) Two of these statements are true.

50. Which of the following is paramagnetic?
A) O2–
B) O2+
C) O2
D) N2
E) At least two of these are paramagnetic.
51. Which of the following is diamagnetic?
A) O2–
B) F2+
C) B2
D) N2
E) NO
52. For how many of B2, C2, P2, and F2 does bond order decrease if one electron is removed from the neutral molecule?
A) 0
B) 1
C) 2
D) 3
E) 4
53. Which of the following statements is false?
A) Atoms or molecules with an even number of electrons are diamagnetic.
B) Atoms or molecules with an odd number of electrons are paramagnetic.
C) Paramagnetism cannot be deduced from the Lewis structure of a molecule alone.
D) Paramagnetic molecules are attracted toward a magnetic field.
E) N2 molecules are diamagnetic.
54. For how many of the following does the bond order decrease if you add one electron to the neutral molecule? B2, Si2, P2, F2
A) 0
B) 1
C) 2
D) 3
E) 4
55. Which of the following species is paramagnetic?
A) C2
B) B2
C) N2
D) H2
E) none of these
56. The fact that O2 is paramagnetic can be explained by
A) the Lewis structure of O2.
B) resonance.
C) a violation of the octet rule.
D) the molecular-orbital diagram for O2.
E) hybridization of atomic orbitals in O2.
57. The molecular-orbital electron configuration below (ls)2 (ls*)2 (2s)2 (2s*)2 (2p)4 (2p)2 applies to which of the following molecules?
A) F2
B) O2
C) BC
D) NO
E) CO

58. Which of the following electron distributions among the molecular orbitals best describes the NO molecule? | 2s | 2s* | 2py = 2px | 2pz | 2py* = 2px* | 2pz* | I. | 2 | 2 | 4 | 2 | 4 | 2 | II. | 2 | 2 | 4 | 2 | 4 | 1 | III. | 2 | 2 | 4 | 1 | 3 | 0 | IV. | 2 | 2 | 4 | 2 | 2 | 0 | V. | 2 | 2 | 4 | 2 | 1 | 0 |

A) I
B) II
C) III
D) IV
E) V
59. Consider the molecular-orbital energy-level diagrams for O2 and NO. Which of the following is true? I. Both molecules are paramagnetic. II. The bond strength of O2 is greater than the bond strength of NO. III. NO is an example of a homonuclear diatomic molecule. IV. The ionization energy of NO is smaller than the ionization energy of NO+.
A) I only
B) I and II only
C) I and IV
D) II and III
E) I, II, and IV
60. In the molecular-orbital description of CO,
A) the highest energy electrons occupy antibonding orbitals.
B) six molecular orbitals contain electrons.
C) there are two unpaired electrons.
D) the bond order is 3.
E) All of these are false.
61. Consider the molecular-orbital description of the NO– anion. Which of the following statements is false?
A) NO– is paramagnetic.
B) NO– is isoelectronic with CO.
C) The bond energy in NO+ is greater than the bond energy in NO–.
D) The bond order in NO– is 2.
E) All of these statements are false.
62. The bond order in the NO+ ion is
A) 1
B) 1.5
C) 2.5
D) 3
E) 2
63. How many electrons are involved in pi bonding in benzene, C6H6?
A) 12
B) 30
C) 3
D) 6
E) 18
64. Which of the following statements about the CO32– ion is false?
A) The orbitals on the carbon atom are sp2 hybridized.
B) The ion is expected to be diamagnetic.
C) One C–O bond is shorter than the others.
D) The ion has a total of 24 electrons.
E) It has a planar molecular geometry.

1. | B | 11. | C | 21. | B | 31. | B | 41. | C | 51. | D | 61. | B | 2. | C | 12. | A | 22. | C | 32. | B | 42. | D | 52. | D | 62. | D | 3. | D | 13. | E | 23. | C | 33. | A | 43. | C | 53. | A | 63. | D | 4. | C | 14. | E | 24. | D | 34. | E | 44. | E | 54. | C | 64. | C | 5. | A | 15. | B | 25. | A | 35. | B | 45. | A | 55. | B | | | 6. | A | 16. | B | 26. | D | 36. | A | 46. | A | 56. | D | | | 7. | E | 17. | E | 27. | B | 37. | C | 47. | C | 57. | E | | | 8. | C | 18. | B | 28. | D | 38. | E | 48. | A | 58. | E | | | 9. | E | 19. | C | 29. | B | 39. | B | 49. | E | 59. | C | | | 10. | D | 20. | A | 30. | B | 40. | C | 50. | E | 60. | D | | |