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Chemistry Atoms First 1st Edition Burdge Overby – Test bank
Chapter 6: Representing Molecules
1. | The Lewis dot symbol consists of the symbol for the element surrounded by dot(s). What does the symbol represent? | |||
A) | Electron configuration | D) | Atomic mass | |
B) | Valence electrons | E) | Nucleus and core electrons | |
C) | Atomic number | |||
Ans: E Difficulty: Easy |
2. | The Lewis dot symbol consists of the symbol for the element surrounded by dot(s). What does the dot or dots represent? | |||
A) | Electron configuration | D) | Atomic mass | |
B) | Valence electrons | E) | Core electrons | |
C) | Atomic number | |||
Ans: B Difficulty: Easy |
3. | Which of the following contains ionic bonding? |
A) CO B) SrF2 C) Al D) OCl2 E) HCl | |
Ans: B Difficulty: Easy |
4. | How many electrons are in a single bond? |
A) 0 B) 1 C) 2 D) 4 E) 6 | |
Ans: C Difficulty: Easy |
5. | How many electrons are in a double bond? |
A) 0 B) 1 C) 2 D) 4 E) 6 | |
Ans: D Difficulty: Easy |
6. | How many electrons are in a triple bond? |
A) 0 B) 1 C) 2 D) 4 E) 6 | |
Ans: E Difficulty: Easy |
7. | Arrange the following bonds in order of increasing bond strength. | |||
A) | C–I < C–Br < C–Cl < C–F | D) | C–I < C–Br < C–F< C–Cl | |
B) | C–F < C–Cl < C–Br < C–I | E) | none of these orders is correct | |
C) | C–Br < C–I < C–Cl < C–F | |||
Ans: A Difficulty: Medium |
8. | Select the strongest bond in the following group. |
A) C–S B) C–O C) C=C D) CºN E) C–F | |
Ans: D Difficulty: Easy |
9. | Select the strongest bond in the following group. |
A) C–C B) C–O C) C=C D) CºC E) C–F | |
Ans: D Difficulty: Easy |
10. | Which is the correct order for increasing bond strength? (1) CºC (2) C=C (3) C–C | |||
A) | (3) < (2) < (1) | D) | (1) < (3) < (2) | |
B) | (3) < (1) < (2) | E) | (2) < (3) < (1) | |
C) | (1) < (2) < (3) | |||
Ans: A Difficulty: Easy |
11. | What types of elements undergo covalent bonding? | |||
A) | 1 metal and noble gas | D) | 2 Group IA elements | |
B) | a nonmetal and a metal | E) | an actinide | |
C) | 2 nonmetals | |||
Ans: C Difficulty: Easy |
12. | In which of these substances are the atoms held together by polar covalent bonding? |
A) SrCl2 B) CsCl C) ClF D) TiF2 E) S8 | |
Ans: C Difficulty: Easy |
13. | A polar covalent bond would form in which one of these pairs of atoms? |
A) Cl ¾ Cl B) Si ¾ Si C) Ca ¾ Cl D) Cr ¾ Br E) P ¾ Cl | |
Ans: E Difficulty: Easy |
14. | A nonpolar covalent bond (i.e., pure covalent) would form in which of these pairs of atoms? |
A) Na ¾ Cl B) H ¾ Cl C) Li ¾ Br D) Se ¾ Br E) Br ¾ Br | |
Ans: E Difficulty: Easy |
15. | Which of these covalent bonds is the most polar (i.e., highest percent ionic character)? |
A) Al ¾ I B) Si ¾ I C) Al ¾ Cl D) Si ¾ Cl E) Si ¾ P | |
Ans: C Difficulty: Medium |
16. | The covalent bond with the greatest polarity would form in which of these atom pairs? |
A) Br ¾ Br B) S ¾ O C) C ¾ P D) C ¾ O E) B ¾ O | |
Ans: E Difficulty: Medium |
17. | In which of these pairs of atoms would the bond be the least polar (i.e., lowest percent ionic character)? |
A) C ¾ Cl B) C ¾ C C) C ¾ H D) O ¾ C E) N ¾ C | |
Ans: B Difficulty: Medium |
18. | Which of these elements has the greatest electronegativity? |
A) Na B) As C) Ga D) Cs E) Sb | |
Ans: B Difficulty: Medium |
19. | Which of these atoms is the most electronegative? |
A) Li B) Cs C) P D) As E) Ge | |
Ans: C Difficulty: Medium |
20. | Which of these elements is the least electronegative? |
A) Sr B) V C) Ni D) P E) I | |
Ans: A Difficulty: Medium |
21. | Which of the following elements is the most electronegative? |
A) S B) Ru C) Si D) Te E) Cs | |
Ans: A Difficulty: Medium |
22. | Which of the following elements is the least electronegative? |
A) Si B) Se C) S D) Sc E) Sr | |
Ans: E Difficulty: Medium |
23. | Arrange aluminum, nitrogen, phosphorus and indium in order of increasing electronegativity. | |||
A) | Al < In < N < P | D) | In < P < Al < N | |
B) | Al < In < P < N | E) | None of these orders is correct. | |
C) | In < Al < P < N | |||
Ans: C Difficulty: Medium |
24. | Arrange calcium, rubidium, sulfur, and arsenic in order of decreasing electronegativity. | |||
A) | S > As > Rb > Ca | D) | As > S > Ca > Rb | |
B) | S > As > Ca > Rb | E) | None of these orders is correct. | |
C) | As > S > Rb > Ca | |||
Ans: B Difficulty: Medium |
25. | Based on electronegativity trends in the periodic table, predict which of the following compounds will have the greatest % ionic character in its bonds. |
A) H2O B) LiI C) CaO D) RbF E) HCl | |
Ans: D Difficulty: Medium |
26. | What is the magnitude of the partial positive and partial negative charges in the HBr molecule? (1D = 3.36 ´ 10–30 C m; 1e– = 1.6022 ´ 10–19 C; bond length HBr = 1.41 angstroms; Dipole Moment HBr = 0.82D) | |||
A) | –0.36 and +0.36 | D) | –0.121 and +0.121 | |
B) | –0.14 and +0.14 | E) | –2.73 and +2.73 | |
C) | –0.273 and +0.273 | |||
Ans: D Difficulty: Medium |
27. | What is the magnitude of the partial positive and partial negative charges in the HI molecule? (1D = 3.36 ´ 10–30 C m; 1e– = 1.6022 ´ 10–19 C; bond length HI = 1.61 angstroms; Dipole Moment HI = 0.44 D) | |||
A) | –0.76 and +0.76 | D) | –0.6 and +0.6 | |
B) | –0.057 and +0.057 | E) | –0.911 and +0.911 | |
C) | –1.22 and +1.22 | |||
Ans: B Difficulty: Medium |
28. | The total number of bonding electrons in a molecule of formaldehyde (H2CO) is |
A) 3 B) 4 C) 6 D) 8 E) 18 | |
Ans: D Difficulty: Medium |
29. | The total number of lone pairs in NCl3 is |
A) 6 B) 8 C) 9 D) 10 E) 13 | |
Ans: D Difficulty: Medium |
30. | The Lewis structure for CS2 is: |
A) B) C) D) | |
Ans: C Difficulty: Medium |
31. | The Lewis structure for a chlorate ion, ClO3–, should show ____ single bond(s), ____ double bond(s), and ____ lone pair(s). |
A) 2, 1, 10 B) 3, 0, 9 C) 2, 1, 8 D) 3, 0, 10 E) 2, 1, 9 | |
Ans: D Difficulty: Difficult |
32. | Which of these Lewis structures is incorrect? |
A) a B) b C) c D) d E) e | |
Ans: E Difficulty: Difficult |
33. | Which of these choices is a correct Lewis structure for ozone, O3? |
A) a B) b C) c D) d E) e | |
Ans: D Difficulty: Medium |
34. | Which one of the following Lewis structures is definitely incorrect?
|
A) a B) b C) c D) d E) e | |
Ans: B Difficulty: Difficult |
35. | Hydrazine, N2H4, is a good reducing agent that has been used as a component in rocket fuels. Select its Lewis structure.
|
A) a B) b C) c D) d E) none of these choices is correct | |
Ans: C Difficulty: Difficult |
36. | Select the correct Lewis structure for nitrogen trifluoride, NF3.
|
A) a B) b C) c D) d E) e | |
Ans: A Difficulty: Medium |
37. | Select the correct Lewis structure for NOCl, a reactive material used as an ionizing solvent.
|
A) a B) b C) c D) d E) none of these choices is correct | |
Ans: B Difficulty: Difficult |
38. | The formal charge on the sulfur atom in the resonance structure of sulfur dioxide which has one single bond and one double bond is |
A) 0 B) +1 C) –1 D) +2 E) –2 | |
Ans: B Difficulty: Difficult |
39. | What is the formal charge on phosphorus in a Lewis structure for the phosphate ion that satisfies the octet rule? |
A) –2 B) –1 C) 0 D) +1 E) +2 | |
Ans: D Difficulty: Difficult |
40. | In the best Lewis structure for the fulminate ion, CNO–, what is the formal charge on the central nitrogen atom? |
A) +2 B) +1 C) 0 D) –1 E) –2 | |
Ans: B Difficulty: Difficult |
41. | In the Lewis structure of the iodate ion, IO3–, that satisfies the octet rule, the formal charge on the central iodine atom is |
A) +2 B) +1 C) 0 D) –1 E) –2 | |
Ans: A Difficulty: Difficult |
42. | Select the Lewis structure for XeO2F2 which correctly minimizes formal charges.
|
A) a B) b C) c D) d E) e | |
Ans: B Difficulty: Difficult |
43. | In the following Lewis structure for ClO3F, chlorine has a formal charge of ____ and an oxidation number of ____.
|
A) 7, 7 B) 7, –1 C) 1, 1 D) 1, –1 E) 1, 7 | |
Ans: E Difficulty: Difficult |
44. | In which one of the following structures does the central atom have a formal charge of +2?
|
A) a B) b C) c D) d E) e | |
Ans: B Difficulty: Difficult |
45. | The formal charge on Cl in the structure shown for the perchlorate ion is
|
A) –2 B) –1 C) 0 D) +1 E) +2 | |
Ans: D Difficulty: Difficult |
46. | The number of resonance structures for the sulfur dioxide molecule that satisfy the octet rule is |
A) 1 B) 2 C) 3 D) 4 E) None of these | |
Ans: B Difficulty: Difficult |
47. | The number of resonance structures for the nitrate ion that satisfy the octet rule is |
A) 1 B) 2 C) 3 D) 4 E) None of these | |
Ans: C Difficulty: Difficult |
48. | In which one of the following is the best Lewis structure a resonance structure? |
A) SO3 B) BF3 C) I3– D) SCO (C = central atom) E) SO32– | |
Ans: A Difficulty: Difficult |
49. | In which one of the following species is the central atom (the first atom in the formula) likely to violate the octet rule? |
A) BF4– B) XeO3 C) SiCl4 D) NH3 E) CH2Cl2 | |
Ans: B Difficulty: Difficult |
50. | Which of the following atoms can expand its valence shell when bonding? |
A) N B) C C) O D) P E) Al | |
Ans: D Difficulty: Medium |
51. | Which of these substances will display an incomplete octet in its Lewis structure? |
A) CO2 B) Cl2 C) ICl D) NO E) SO2 | |
Ans: D Difficulty: Medium |
52. | Which of these elements is most likely to exhibit an expanded octet in its compounds? |
A) O B) S C) Na D) C E) N | |
Ans: B Difficulty: Medium |
53. | Which response includes all the molecules below that do not follow the octet rule? (1) H2S (2) BCl3 (3) PH3 (4) SF4 |
A) (2) and (4) B) (2) and (3) C) (1) and (2) D) (3) and (4) E) (1) and (4) | |
Ans: A Difficulty: Difficult |
54. | Which of these molecules has an atom with an expanded octet? |
A) HCl B) AsCl5 C) ICl D) NCl3 E) Cl2 | |
Ans: B Difficulty: Medium |
55. | Which molecule has a Lewis structure that does not obey the octet rule? |
A) N2O B) CS2 C) PH3 D) CCl4 E) NO2 | |
Ans: E Difficulty: Medium |
56. | Ionic compounds tend to form between metals and nonmetals when electrons are transferred from an element with high ionization energy (metal) to an element with a low electron affinity (nonmetal). |
Ans: False Difficulty: Medium |
57. | Lewis theorized the octet rule to describe chemical bonding where atoms lose, gain, or share electrons in order to achieve a noble gas configuration. |
Ans: True Difficulty: Easy |
58. | Only valence electrons are shown in the Lewis structure held together by covalent bonds. |
Ans: True Difficulty: Easy |
59. | A double bond can not exist between a carbon atom and an oxygen atom. |
Ans: False Difficulty: Easy |
60. | A triple bond can not exist between a carbon atom and a hydrogen atom. |
Ans: True Difficulty: Easy |
61. | Unshared electrons are always shown in pairs around an atom. |
Ans: False Difficulty: Easy |
62. | The octet rule works best for elements in the 3rd period of the periodic table. |
Ans: False Difficulty: Medium |
63. | Multiple bonds are longer than single bonds. |
Ans: False Difficulty: Easy |
64. | Single bonds are stronger than multiple bonds. |
Ans: False Difficulty: Easy |
65. | What theory describes atoms losing, gaining, or sharing electrons to achieve a noble gas configuration? | |
Ans: | octet rule | |
Difficulty: Easy |
66. | What is the distance between the nuclei of two covalently bonded atoms in a molecule? | |
Ans: | bond length | |
Difficulty: Easy |
67. | What term describes the ability of an atom in a compound to pull the electrons to itself? | |
Ans: | electronegativity | |
Difficulty: Easy |
68. | How many lone pairs of electrons are on the central atom in the Lewis structure for NH3? | |
Ans: | 1 | |
Difficulty: Easy |
69. | Give the equation for percent ionic character. | |
Ans: | (observed dipole moment/calculated dipole moment assuming discrete charges) ´ 100% | |
Difficulty: Medium |
70. | Give the equation for formal charge. | |
Ans: | # valence electrons – (1/2)(bonded electrons) – lone electrons | |
Difficulty: Medium |
71. | The number of dots in the Lewis dot symbol for a main group element is the same as the ___________ ___________. | |
Ans: | group number | |
Difficulty: Easy |
72. | ___________ ___________ of atoms interact to form compounds. | |
Ans: | Valence electrons | |
Difficulty: Easy |
73. | In the Lewis dot symbol, the element symbol represents the ________ _________ and the dots represent the __________ ___________. | |
Ans: | core electrons; valence electrons | |
Difficulty: Easy |
74. | A triple bond arises when two atoms share ___________ pairs of electrons. | |
Ans: | three | |
Difficulty: Easy |
75. | A single bond between two atoms represents ________ pair(s) of electrons | |
Ans: | one | |
Difficulty: Easy |
76. | ______________ is a representation of covalent bonding in which shared electron pairs are shown either as dashes or as pairs of dots between two atoms and unshared electrons are shown as dots around the individual atoms. | |
Ans: | Lewis structure | |
Difficulty: Easy |
77. | Using appropriate, real examples to illustrate your answer, describe the correlation between bond energy and bond length for a series of single bonds. | |
Ans: | The bonds between carbon, C, and the halogens, X (X = F, Cl, Br, I) can be used as an examples. The size of X increases as one moves down the group. This means that the C–X bond length will become correspondingly longer. As this occurs the bond becomes weaker. Thus, the C–I bond is the longest and weakest, C–F the shortest and strongest of the series. | |
Difficulty: Medium |
78. | Using appropriate, real examples to illustrate your answer, describe the correlation between bond energy and bond length for a series of varying bond order. | |
Ans: | Carbon and oxygen form single, double and triple bonds. The CºO bond in carbon monoxide is roughly three times as strong as the C–O single bond, while the C=O bond is about twice as strong as the single bond. The bond energy is approximately proportional to the bond order. | |
Difficulty: Medium |
79. | Describe in brief how electronegativity values can be used to predict the percent ionic character of a bond between two atoms. | |
Ans: | Take the electronegativity difference (DEN) of the bonded atoms. The larger the difference between their electronegativities, the more ionic will be the nature of the bond. If DEN = 0, the bond will be pure covalent. | |
Difficulty: Medium |
Chapter 7: Molecular Geometry and Bonding Theories
1. | What does VSEPR model mean? | |
A) | Very Specific Electron and Proton Repair model | |
B) | Variable Selective of Electron and PRotons | |
C) | Valence Shell for Every Proton | |
D) | Very Selective Electron PaiR theory | |
E) | Valence Shell Electron-Pair Repulsion | |
Ans: E Difficulty: Easy |
2. | Which of the following is required for determination of the VSEPR model and the molecular shape? | |||
A) | Atomic mass | D) | Lewis structure | |
B) | # of protons | E) | None of the answers is correct | |
C) | Oxidation number | |||
Ans: D Difficulty: Easy |
3. | According to the VSEPR theory, the shape of the SO3 molecule is | |||
A) | pyramidal. | D) | distorted tetrahedron (seesaw). | |
B) | tetrahedral. | E) | square planar. | |
C) | trigonal planar. | |||
Ans: C Difficulty: Medium |
4. | What is the molecular shape of the CH4 molecule? | |||
A) | tetrahedral. | D) | square planar. | |
B) | trigonal pyramidal | E) | distorted tetrahedron (seesaw). | |
C) | trigonal planar. | |||
Ans: A Difficulty: Easy |
5. | Use VSEPR theory to predict the shape of the PCl3 molecule. |
A) linear B) bent C) trigonal planar D) trigonal pyramidal E) tetrahedral | |
Ans: D Difficulty: Medium |
6. | What is the molecular shape of the H2O molecule? | |||
A) | tetrahedral. | D) | square planar. | |
B) | trigonal pyramidal | E) | distorted tetrahedron (seesaw). | |
C) | bent. | |||
Ans: C Difficulty: Easy |
7. | What is the molecular shape of the IBr3 molecule? | |||
A) | tetrahedral. | D) | trigonal planar. | |
B) | T-shaped | E) | distorted tetrahedron (seesaw). | |
C) | bent. | |||
Ans: B Difficulty: Medium |
8. | According to the VSEPR theory, the molecular shape of the carbonate ion, CO32 –, is | |||
A) | square planar. | D) | trigonal planar. | |
B) | tetrahedral. | E) | octahedral. | |
C) | pyramidal. | |||
Ans: D Difficulty: Medium |
9. | According to the VSEPR theory, the molecular shape of SiCl4 is |
A) linear. B) trigonal planar. C) bent. D) tetrahedral. E) trigonal pyramidal. | |
Ans: D Difficulty: Easy |
10. | According to the VSEPR theory, the molecular shape of ammonia is |
A) linear. B) trigonal planar. C) bent. D) tetrahedral. E) trigonal pyramidal. | |
Ans: E Difficulty: Medium |
11. | According to the VSEPR theory, which one of the following species should be linear? |
A) H2S B) HCN C) BF3 D) H2CO E) SO3 | |
Ans: B Difficulty: Medium |
12. | According to VSEPR theory, which one of the following molecules should have a shape that is trigonal bipyramidal? |
A) SF4 B) XeF4 C) NF3 D) SF6 E) PF5 | |
Ans: E Difficulty: Medium |
13. | Which one of the following molecules has tetrahedral geometry? |
A) XeF4 B) BF3 C) AsF5 D) CF4 E) NH3 | |
Ans: D Difficulty: Medium |
14. | Predict the geometry around the central atom in PO43–. | |||
A) | trigonal planar. | D) | trigonal bipyramidal. | |
B) | trigonal pyramidal. | E) | octahedral. | |
C) | tetrahedral. | |||
Ans: C Difficulty: Medium |
15. | Predict the geometry around the central atom in SO32–. | |||
A) | trigonal planar. | D) | trigonal bipyramidal. | |
B) | trigonal pyramidal. | E) | octahedral. | |
C) | tetrahedral. | |||
Ans: B Difficulty: Medium |
16. | What is the total number of electron domains for a molecule having a trigonal pyramidal molecular geometry such as NH3? |
A) 5 B) 2 C) 3 D) 4 E) 6 | |
Ans: D Difficulty: Medium |
17. | What is the total number of electron domains for a molecule having a T-shaped pyramidal molecular geometry such as BrF3? |
A) 5 B) 2 C) 3 D) 4 E) 6 | |
Ans: A Difficulty: Medium |
18. | What is the total number of electron domains for a molecule having a square pyramidal molecular geometry such as ClF5? |
A) 5 B) 2 C) 3 D) 4 E) 6 | |
Ans: E Difficulty: Medium |
19. | What is the total number of electron domains for a molecule having a square planar molecular geometry such as XeBr4? |
A) 5 B) 2 C) 3 D) 4 E) 6 | |
Ans: E Difficulty: Medium |
20. | What is the number of lone electron pairs on the central atom of a molecule having a molecular geometry of seesaw-shaped such as SF4? |
A) 1 B) 2 C) 3 D) 4 E) 6 | |
Ans: A Difficulty: Medium |
21. | What is the number of lone electron pairs on the central atom of a molecule having a trigonal pyramidal molecular geometry such as NH3? |
A) 1 B) 2 C) 3 D) 0 E) 4 | |
Ans: A Difficulty: Medium |
22. | What is the number of lone electron pairs on the central atom of a molecule having a linear molecular geometry such as CO2? |
A) 1 B) 2 C) 3 D) 0 E) 4 | |
Ans: D Difficulty: Medium |
23. | What is the number of lone electron pairs on the central atom of a molecule having a linear molecular geometry such as ClF2–? |
A) 1 B) 2 C) 3 D) 0 E) 4 | |
Ans: C Difficulty: Medium |
24. | According to VSEPR theory, a molecule with the general formula AX3Eo will have a ______ molecular shape. |
A) linear. B) bent. C) trigonal planar. D) tetrahedral. E) trigonal pyramidal. | |
Ans: C Difficulty: Medium |
25. | According to VSEPR theory, a molecule with the general formula AX5Eo will have a ______ molecular shape. | |||
A) | tetrahedral. | D) | trigonal bipyramidal. | |
B) | trigonal planar. | E) | see-saw. | |
C) | trigonal pyramidal. | |||
Ans: D Difficulty: Medium |
26. | According to VSEPR theory, a molecule with the general formula AX2E2 will have a _____ molecular shape. |
A) linear. B) bent. C) trigonal planar. D) tetrahedral. E) see-saw. | |
Ans: B Difficulty: Medium |
27. | According to VSEPR theory, a molecule with the general formula AX4E2 will have a _____ molecular shape. | |||
A) | tetrahedral. | D) | octahedral. | |
B) | square pyramidal. | E) | see-saw. | |
C) | square planar. | |||
Ans: C Difficulty: Medium |
28. | According to VSEPR theory, a molecule with the general formula AX5E will have a ______ molecular shape. | |||
A) | tetrahedral. | D) | octahedral. | |
B) | trigonal bipyramidal | E) | see-saw. | |
C) | square pyramidal | |||
Ans: C Difficulty: Medium |
29. | What is the molecular shape of N2O as predicted by the VSEPR theory?
|
A) trigonal pyramidal B) trigonal planar C) angular D) bent E) linear | |
Ans: E Difficulty: Medium |
30. | What is the molecular shape of the thiocyanate anion, SCN–, as predicted by the VSEPR theory? (Carbon is the central atom.) |
A) linear B) bent C) angular D) trigonal E) none of these choices is correct | |
Ans: A Difficulty: Medium |
31. | What is the molecular shape of BeH2 as predicted by the VSEPR theory? |
A) linear B) bent C) angular D) trigonal E) none of these choices is correct | |
Ans: A Difficulty: Medium |
32. | What is the molecular shape of NOCl as predicted by the VSEPR theory?
|
A) linear B) trigonal planar C) bent D) tetrahedral E) trigonal pyramidal | |
Ans: C Difficulty: Medium |
33. | What is the molecular shape of NO2– as predicted by the VSEPR theory? |
A) linear B) trigonal planar C) bent D) tetrahedral E) resonant | |
Ans: C Difficulty: Medium |
34. | What is the molecular shape of ClO3F as predicted by the VSEPR theory?
|
|||
A) | trigonal pyramidal | D) | tetrahedral | |
B) | square planar | E) | octahedral | |
C) | square pyramidal | |||
Ans: D Difficulty: Medium |
35. | What is the molecular shape of HOF as predicted by the VSEPR theory? |
A) trigonal pyramidal B) trigonal C) tetrahedral D) linear E) bent | |
Ans: E Difficulty: Medium |
36. | What is the molecular shape of XeO2F2 as predicted by the VSEPR theory?
|
|||
A) | square planar | D) | see-saw | |
B) | tetrahedral | E) | octahedral | |
C) | square pyramidal | |||
Ans: D Difficulty: Medium |
37. | What is the molecular shape of ClF2– as predicted by the VSEPR theory? |
A) linear B) bent C) see-saw D) T-shaped E) L-shaped | |
Ans: A Difficulty: Medium |
38. | What is the molecular shape of SiF62– as predicted by the VSEPR theory?
|
|||
A) | trigonal bipyramidal | D) | see-saw | |
B) | hexagonal | E) | octahedral | |
C) | tetrahedral | |||
Ans: E Difficulty: Medium |
39. | Use VSEPR theory to predict the electron group arrangement around iodine, the central atom in the ion IF2–. | |||
A) | octahedral | D) | trigonal planar | |
B) | trigonal bipyramidal | E) | bent | |
C) | tetrahedral | |||
Ans: B Difficulty: Medium |
40. | Use VSEPR theory to decide which one of the following molecules and ions will definitely have at least one 90° bond angle in it. (In each case except water, the central atom is the first one in the formula.) |
A) AlCl4– B) NH3 C) PCl5 D) CO2 E) H2O | |
Ans: C Difficulty: Medium |
41. | What is the approximate bond angle for CCl4? |
A) 90° B) 109.5° C) 120° D) 145° E) 180° | |
Ans: B Difficulty: Easy |
42. | The F – S – F bond angles in SF6 are |
A) 90° and 180° B) 109.5° C) 120° D) 180° E) 90° and 120° | |
Ans: A Difficulty: Medium |
43. | What is the approximate bond angle for NH3? |
A) 90° B) 109.5° C) 120° D) 107° E) 105° | |
Ans: D Difficulty: Medium |
44. | What is the approximate bond angle for CO2? |
A) 90° B) 109.5° C) 120° D) 107° E) 180° | |
Ans: E Difficulty: Medium |
45. | What is the approximate bond angle for H2O? |
A) 90° B) 109.5° C) 120° D) 107° E) 105° | |
Ans: E Difficulty: Medium |
46. | Predict the ideal bond angles in AsCl3 using the molecular shape given by the VSEPR theory. |
A) 90° B) 109° C) 120° D) 180° E) between 110 and 120° | |
Ans: B Difficulty: Medium |
47. | Predict the actual bond angles in BrF3 using the VSEPR theory. | |||
A) | more than 120° | D) | between 90° and 109° | |
B) | exactly 120° | E) | less than 90° | |
C) | between 109° and 120° | |||
Ans: E Difficulty: Medium |
48. | What is the approximate bond angle for CH4? |
A) 90° B) 109.5° C) 120° D) 107° E) 105° | |
Ans: B Difficulty: Easy |
49. | How do you describe the molecular geometry of a molecule that does not have a central atom? | |
A) | Describe the molecular geometry around the most electronegative atom. | |
B) | Describe the molecular geometry around all non-hydrogen atoms. | |
C) | Describe the molecular geometry around the most electropositive atom. | |
D) | Describe the molecular geometry around the atom with the largest atomic radius. | |
E) | Describe the molecular geometry around the atom with the largest bond angle. | |
Ans: B Difficulty: Medium |
50. | Which one of the following molecules is nonpolar? |
A) NH3 B) OF2 C) CH3Cl D) H2O E) BeCl2 | |
Ans: E Difficulty: Difficult |
51. | Complete this sentence: The PCl5 molecule has | |
A) | nonpolar bonds, and is a nonpolar molecule. | |
B) | nonpolar bonds, but is a polar molecule. | |
C) | polar bonds, and is a polar molecule. | |
D) | polar bonds, but is a nonpolar molecule. | |
Ans: D Difficulty: Difficult |
52. | Which one of the following molecules is nonpolar? |
A) CO2 B) BF3 C) KCl D) IBr3 E) CHCl3 | |
Ans: A Difficulty: Difficult |
53. | Which one of the following molecules has a zero dipole moment? |
A) CO B) CH2Cl2 C) SO3 D) SO2 E) NH3 | |
Ans: C Difficulty: Difficult |
54. | What is the dipole moment for CO2? | |||
A) | –1 | D) | need more information | |
B) | 0 | E) | None of the answers is correct | |
C) | +1 | |||
Ans: B Difficulty: Medium |
55. | Which one of the following molecules is polar? |
A) PBr5 B) CCl4 C) BrF5 D) XeF2 E) XeF4 | |
Ans: C Difficulty: Difficult |
56. | Predict the molecular geometry and polarity of the SO2 molecule. | |||
A) | linear, polar | D) | bent, nonpolar | |
B) | linear, nonpolar | E) | None of the above. | |
C) | bent, polar | |||
Ans: C Difficulty: Difficult |
57. | Predict the geometry and polarity of the CS2 molecule. | |||
A) | linear, polar | D) | bent, nonpolar | |
B) | linear, nonpolar | E) | bent, polar | |
C) | tetrahedral, nonpolar | |||
Ans: B Difficulty: Difficult |
58. | Which one of the following molecules is polar? |
A) CH4 B) CHBr3 C) F2 D) CBr4 E) CO2 | |
Ans: B Difficulty: Difficult |
59. | Which of the following molecules has a net dipole moment? |
A) BeCl2 B) SF2 C) KrF2 D) CO2 E) CCl4 | |
Ans: B Difficulty: Difficult |
60. | Which of the following has no net dipole moment? |
A) N2O B) NF3 C) H2Se D) TeO3 E) CH3Cl | |
Ans: D Difficulty: Difficult |
61. | Which of the following atoms, in the ground state, has unpaired electrons? |
A) Ca B) Ne C) Mg D) He E) C | |
Ans: E Difficulty: Easy |
62. | Which of the following atoms, in the ground state, does not have unpaired electrons? |
A) P B) Na C) Ne D) C E) S | |
Ans: C Difficulty: Easy |
63. | How many bonds should an oxygen atom form? |
A) 1 B) 2 C) 3 D) 6 E) 4 | |
Ans: B Difficulty: Easy |
64. | How many bonds should a carbon atom form? |
A) 1 B) 2 C) 3 D) 6 E) 4 | |
Ans: E Difficulty: Easy |
65. | How many bonds should a fluorine atom form? |
A) 1 B) 2 C) 3 D) 6 E) 4 | |
Ans: A Difficulty: Easy |
66. | Indicate the type of hybrid orbitals used by the central atom in PCl3. |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: C Difficulty: Difficult |
67. | Indicate the type of hybrid orbitals used by the central atom in CCl4. |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: D Difficulty: Medium |
68. | Indicate the type of hybrid orbitals used by the central atom in SF6. |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: E Difficulty: Medium |
69. | What is the hybridization of the As atom in the AsF5 molecule? |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: D Difficulty: Medium |
70. | What is the hybridization on the central atom in NO3–? |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: B Difficulty: Difficult |
71. | In which one of the following molecules is the central atom sp2 hybridized? |
A) SO2 B) N2O C) BeCl2 D) NF3 E) PF5 | |
Ans: A Difficulty: Difficult |
72. | What is the hybridization of As in the AsF4– ion? |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: D Difficulty: Difficult |
73. | What is the hybridization of the central atom in ClO3–? |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: C Difficulty: Difficult |
74. | The hybridization of the central nitrogen atom in the molecule N2O is |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: A Difficulty: Difficult |
75. | A molecule with the formula AX2 uses _________ to form its bonds. | |||
A) | sp hybrid orbitals | D) | sp3d hybrid orbitals | |
B) | sp2 hybrid orbitals | E) | sp3d2 hybrid orbitals | |
C) | sp3 hybrid orbitals | |||
Ans: A Difficulty: Difficult |
76. | A molecule with the formula AX4 uses _________ to form its bonds. | |||
A) | sp hybrid orbitals | D) | sp3d hybrid orbitals | |
B) | sp2 hybrid orbitals | E) | sp3d2 hybrid orbitals | |
C) | sp3 hybrid orbitals | |||
Ans: C Difficulty: Difficult |
77. | A molecule with the formula AX4E2 uses _________ to form its bonds. | |||
A) | sp hybrid orbitals | D) | sp3d hybrid orbitals | |
B) | sp2 hybrid orbitals | E) | sp3d2 hybrid orbitals | |
C) | sp3 hybrid orbitals | |||
Ans: E Difficulty: Difficult |
78. | Carbon uses ______ hybrid orbitals in ClCN. |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: A Difficulty: Difficult |
79. | Valence bond theory predicts that carbon will use _____ hybrid orbitals in the carbonate anion, CO32–. |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: B Difficulty: Difficult |
80. | Valence bond theory predicts that sulfur will use _____ hybrid orbitals in sulfur dioxide, SO2. |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: B Difficulty: Difficult |
81. | When PCl5 solidifies it forms PCl4+ cations and PCl6– anions. According to valence bond theory, what hybrid orbitals are used by phosphorus in the PCl4+ cations? |
A) sp B) sp2 C) sp3 D) sp3d E) sp3d2 | |
Ans: C Difficulty: Difficult |
82. | Valence bond theory predicts that iodine will use _____ hybrid orbitals in ICl2–. |
A) sp2 B) sp3 C) sp3d D) sp3d2 E) none of these choices is correct | |
Ans: C Difficulty: Difficult |
83. | Which one of the following statements about orbital hybridization is incorrect? | |
A) | The carbon atom in CH4 is sp3 hybridized. | |
B) | The carbon atom in CO2 is sp hybridized. | |
C) | The nitrogen atom in NH3 is sp2 hybridized. | |
D) | sp2 hybrid orbitals are coplanar, and at 120° to each other. | |
E) | sp hybrid orbitals lie at 180° to each other. | |
Ans: C Difficulty: Difficult |
84. | For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom? | |||
A) | BeCl2 sp2 | D) | C2H2 sp | |
B) | SiH4 sp3 | E) | H2O sp3 | |
C) | BF3 sp2 | |||
Ans: A Difficulty: Difficult |
85. | Determine the shape (geometry) of PCl3 and then decide on the appropriate hybridization of phosphorus in this molecule. (Phosphorus is the central atom.) |
A) sp3 B) sp2 C) sp D) sp3d E) sp3d2 | |
Ans: A Difficulty: Difficult |
86. | The number of pi bonds in the molecule below is |
A) 1 B) 2 C) 3 D) 5 E) 9 | |
Ans: C Difficulty: Medium |
87. | The number of pi bonds in the molecule below is |
A) 2 B) 4 C) 6 D) 10 E) 15 | |
Ans: B Difficulty: Medium |
88. | According to valence bond theory, the triple bond in ethyne (acetylene, C2H2) consists of | |||
A) | three s bonds and no p bonds. | D) | no s bonds and three p bonds. | |
B) | two s bonds and one p bond. | E) | none of these choices is correct | |
C) | one s bond and two p bonds. | |||
Ans: C Difficulty: Medium |
89. | The number of pi bonds in the oxalate ion (C2O42–) is |
A) 1 B) 2 C) 3 D) 4 E) 5 | |
Ans: B Difficulty: Difficult |
90. | Consider the species Cl2+, Cl2, and Cl2–. Which of these species will be paramagnetic? | |||
A) | Only Cl2 | D) | Cl2+ and Cl2– | |
B) | Cl2+ and Cl2 | E) | All three are paramagnetic | |
C) | Cl2 and Cl2– | |||
Ans: D Difficulty: Medium |
91. | Consider the species N2–, N2, and N2+. Which of these species will be paramagnetic? | |||
A) | N2 and N2– | D) | Only N2– | |
B) | N2+ and N2 | E) | None are paramagnetic | |
C) | N2+ and N2– | |||
Ans: C Difficulty: Medium |
92. | Which of the following is not true of molecular orbitals? | |
A) | The number of molecular orbitals formed is always equal to the number of atomic orbitals combined. | |
B) | A molecular orbital can accommodate up to two electrons. | |
C) | When electrons are added to orbitals of the same energy, the most stable arrangement is predicted by Hund’s rule. | |
D) | Low-energy molecular orbitals fill before high-energy molecular orbitals fill. | |
E) | For any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms. | |
Ans: E Difficulty: Medium |
93. | The electrons in the delocalized molecular orbitals of benzene (C6H6) | |
A) | are confined between two adjacent bonding atoms. | |
B) | are free to move around the six-membered ring. | |
C) | form the electron pairs in the C–H bonds of the compound. | |
D) | are unevenly distributed through the molecule. | |
E) | are responsible for the fact that the bonds between three pairs of carbon atoms in the ring are longer and stronger than the bonds between the other three pairs of carbon atoms. | |
Ans: B Difficulty: Medium |
94. | According to molecular orbital (MO) theory, the twelve outermost electrons in the O2 molecule are distributed as follows: | |
A) | 12 in bonding MOs, 0 in antibonding MOs. | |
B) | 10 in bonding MOs, 2 in antibonding MOs. | |
C) | 9 in bonding MOs, 3 in antibonding MOs. | |
D) | 8 in bonding MOs, 4 in antibonding MOs. | |
E) | 7 in bonding MOs, 5 in antibonding MOs. | |
Ans: D Difficulty: Medium |
95. | According to molecular orbital theory, what is the bond order in the O2+ ion? |
A) 5.5 B) 5 C) 4 D) 2.5 E) 1.5 | |
Ans: D Difficulty: Medium |
96. | The nitrosonium ion, NO+, forms a number of interesting complexes with nickel, cobalt, and iron. According to molecular orbital theory, which of the following statements about NO+ is correct? | |
A) | NO+ has a bond order of 2 and is paramagnetic. | |
B) | NO+ has a bond order of 2 and is diamagnetic. | |
C) | NO+ has a bond order of 3 and is paramagnetic. | |
D) | NO+ has a bond order of 3 and is diamagnetic. | |
E) | None of these statements is correct. | |
Ans: D Difficulty: Difficult |
97. | The BrF5 molecule has polar bonds and has a net dipole moment. |
Ans: True Difficulty: Medium |
98. | Pi bonds are covalent bonds in which the electron density is concentrated above and below the plane of the nuclei of the bonding atoms. |
Ans: True Difficulty: Easy |
99. | The number of lone pairs of electrons on the central atoms is the main factor that is used to determine the molecular shape or molecular geometry. |
Ans: True Difficulty: Easy |
100. | According to VSEPR theory, a molecule with the general formula AX3E2 (where E represents a lone pair on A) will be trigonal planar. |
Ans: False Difficulty: Medium |
101. | A molecule which contains polar bonds will always have a dipole moment. |
Ans: False Difficulty: Medium |
102. | To make a sp3 hybrid orbital, one s orbital is mixed with 3 p orbitals. |
Ans: True Difficulty: Easy |
103. | The bond angle for a sp hybrid orbital is smaller than the bond angle for a sp2 hybrid orbital. |
Ans: False Difficulty: Medium |
104. | The angles between sp2 hybrid orbitals are 109.5°. |
Ans: False Difficulty: Medium |
105. | Atoms of period 3 and beyond can undergo sp3d 2 hybridization, but atoms of period 2 cannot. |
Ans: True Difficulty: Medium |
106. | In the valence bond treatment, overlap of an s orbital on one atom with an sp3 orbital on another atom can give rise to a s bond. |
Ans: True Difficulty: Medium |
107. | In the valence bond treatment, a p bond is formed when two 2p orbitals overlap side to side |
Ans: True Difficulty: Easy |
108. | According to molecular orbital theory, all diatomic molecules with an even number of electrons will be diamagnetic. |
Ans: False Difficulty: Medium |
109. | To correctly determine the molecular shape of a molecule requires that you first draw the Lewis structure for the molecule. |
Ans: True Difficulty: Easy |
110. | Use VSEPR theory to predict the molecular geometry of H3O+ (hydronium ion). | |
Ans: | trigonal pyramidal | |
Difficulty: Medium |
111. | Use VSEPR theory to predict the molecular geometry of CO32– | |
Ans: | trigonal planar | |
Difficulty: Medium |
112. | The N – N – H bond angles in hydrazine N2H4 are 112°. What is the hybridization of the nitrogen orbitals predicted by valence bond theory? | |
Ans: | sp3. | |
Difficulty: Medium |
113. | How many p-bonds in CH3COCH3? | |
Ans: | one. | |
Difficulty: Medium |
114. | According to the VSEPR theory, will the molecule PF5 be polar or nonpolar? | |
Ans: | nonpolar | |
Difficulty: Medium |
115. | How many electron domains are on the central atom for a sp2 hybridized atom? | |
Ans: | 3 | |
Difficulty: Medium |
116. | How many electron domains are on the central atom for a sp3d hybridized atom? | |
Ans: | 5 | |
Difficulty: Medium |
117. | What name is given to the shape of a molecule with no lone pairs of electrons on the central atom and 6 electron domains on the central atom? | |
Ans: | Octahedral | |
Difficulty: Easy |
118. | The total number of electron domains is used to determine the ___________. | |
Ans: | Electron-Domain Geometry | |
Difficulty: Easy |
119. | The number of lone pairs on the central atoms is used to determine the ____________. | |
Ans: | Molecular Geometry | |
Difficulty: Easy |
120. | Complete the following table.
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Ans: |
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Difficulty: Medium |
121. | ___________ _________ results from parallel overlap of two p orbitals. | |
Ans: | p-bonds | |
Difficulty: Easy |
122. | Water has ___________ number of lone pairs of electrons on the central oxygen. | |
Ans: | two | |
Difficulty: Easy |
123. | ___________ is the electron-domain geometry and _________ is the molecular shape for ammonia. | |
Ans: | tetrahedral and pyramidal | |
Difficulty: Medium |
124. | The bond angle for the carbonate ion is ___________. | |
Ans: | 1200 | |
Difficulty: Medium |
125. | Draw a Lewis structure for PF5 that shows the correct atom arrangement predicted by the VSEPR theory. | |
Ans: | ||
Difficulty: Medium |
126. | The Lewis structure of formaldehyde, CH2O, is shown. Use VSEPR theory to predict the molecular geometry and the H–C–H bond angle. Outline your reasoning.
|
|
Ans: | There are three electron groups around the central atom, carbon. These are a double bond and two single bonds. The molecule is thus of the AX3 type, and its geometry will be trigonal planar. The bond angles will be 120°. | |
Difficulty: Medium |
127. | Draw the Lewis structure of XeF4. Use this structure, in conjunction with VSEPR theory, to predict the shape of this molecule. Outline your reasoning. | |
Ans: | The Lewis structure is shown alongside. The VSEPR formula is AX4E2, and the electron group arrangement is therefore octahedral. The lone pairs will lie at opposite vertices, resulting in a square planar molecular geometry. | |
Difficulty: Difficult |
128. | In one sentence state the basic principle of valence bond theory. | |
Ans: | A covalent bond forms when the orbitals of two atoms overlap and a pair of electrons occupies the region between the nuclei. | |
Difficulty: Easy |
129. | In not more than two sentences, explain when and why chemists make use of the concept of hybridization. | |
Ans: | Chemists postulate hybridization when the observed geometry of a molecule cannot be rationalized in terms of overlap of the s, p and/or d orbitals of the atoms concerned. | |
Difficulty: Medium |
130. | In one sentence state how molecular orbitals are usually obtained. | |
Ans: | By the linear combination (addition or subtraction) of atomic orbitals. | |
Difficulty: Medium |