Name Unit Three MC Practice March 15, 2017

Unit Three: Bonding & Molecular Geometry Name Unit Three MC Practice March 15, 2017 1. What is the hybridization of the oxygen atom in water? a) sp b) sp 2 c) sp 3 d) It is not hybridized 2. When a double bond is formed between two atoms, one of the bonds is a sigma bond and the other is a pi bond. The pi bond is created by the overlap of... a) p orbitals b) sp 3 hybrid orbitals c) sp 2 hybrid orbitals d) s orbitals 3. The central atom in BrF 5 has _?_ bonding pairs of electrons and _?_ non-bonding pairs of electrons. a) 1...5 b) 0...5 c) 5...1 d) 5...0 4. Which of the following molecules does not have a net dipole moment? a) H 2O b) NH 3 c) BrF 5 d) BF 3 5. What is the electron-pair geometry of the central oxygen atom of ozone (O 3)? a) linear b) trigonal planar c) tetrahedral d) trigonal bipyramidal 6. What is the molecular geometry for ammonia (NH 3)? a) saw horse b) trigonal planar c) tetrahedral d) trigonal pyramidal 7. Which of the following best represents the 3-dimensional view of H 2N -1? 8. What is the hybridization of the sulfur atom is SF 4? a) sp 2 b) sp 3 c) sp 3 d d) sp 3 d 2 9. What is the hybridization of the xenon atom in XeF 4? a) sp 2 b) sp 3 c) sp 3 d d) sp 3 d 2 10. According to the octet rule, NO + should contain a: a) single bond b) double bond c) triple bond d) James Bond 1

11. According to the octet rule, the carbon-oxygen bond in the molecule COBr 2, in which carbon is bonded to O and Br atoms, is a: a) single bond b) double bond c) triple bond d) quadruple bond Questions 12 and 13 are based on the XeF 4 molecule. 12. The electron pair geometry around the central atom is: a) trigonal planar b) trigonal bipyramidal c) octahedral d) square planar 13. The molecular geometry is: a) tetrahedral b) trigonal bipyramidal c) seesaw d) square planar 14. Which of the following molecules would have the greatest polarity? a) HF b) HCl c) HBr d) HI 15. Ionic solids will typically be formed between atoms in: a) groups I A and VIII A. b) groups II A and VII A. c) groups VI A and VII A d) groups I A and VI B. 16. For which of the following molecules is an expanded octet necessary to describe the bonding in the molecule? a) H 2 b) PF 5 c) H 2O d) CH 4 17. The geometry of the XeO 4 molecule is best described as: a) square planer b) tetrahedral c) octahedral d) bent Questions 18 through 20 are based on the formaldehyde molecule, CH 2O, where carbon is the central atom and the bond angle H-C-O is 120 degrees. 18. The type of orbitals used on the carbon atom in the formaldehyde mole is: a) sp hybrids b) sp 2 hybrids c) sp 3 hybrids d) sp 3 d hybrids 19. The bond between the carbon and oxygen would be best described as: a) one sigma (s) bond b) two sigma (s) bonds c) one pi (p) bond d) one sigma (s) bond and one pi (p) bond 20. The molecule is best described as: a) a polar molecule containing polar bonds b) a non-polar molecule made up of polar bonds c) a non-polar molecule made up of non-polar bonds d) none of the above 21. Which of the following molecules is NOT polar? a) CCl 4 b) H 2O c) CH 3OH d) NH 3 2

22. The reaction between H 2 and F 2 to form HF is because. a) exothermic; H-F bonds are stronger than H-H and F-F bonds b) exothermic; H-F bonds are weaker than H-H and F-F bonds c) endothermic; H-F bonds are stronger than H-H and F-F bonds d) endothermic; H-F bonds are stronger than H-H and F-F bonds 23. Use the table of bond energies given below to estimate ΔH for the reaction: 2 H2O(g) + 2 Cl2(g) ==> O2(g) + 4 HCl(g) Bond H-H F-F H-F Cl-Cl O=O H-O H-Cl Bond Energy (kj/mol) 436 159 565 243 498 464 431 a) +189kJ b) -280kJ c) +120kJ d) +398kJ 24. Which of the following species require a resonance hybrid for its Lewis structure? a) NH 3 b) CO 3 c) OCl - d) OH - Questions 25 and 26 are based on the following structure showing only the sigma (s) or single bond structure. All bond angles are approximately 120. 25. The type of orbitals on the carbon atom that would account for this geometry are: a)sp hybrid orbitals b) sp 2 hybrid orbitals c) sp 3 hybrid orbitals d) sp 3 d hybrid orbitals 26. The bond between the carbon and oxygen is best described by which of the following? a) one sigma (s) bond b) two sigma (s) bonds c) one sigma (s) and one pi (p) bond d) two pi (p) bonds 27. Estimate ΔH in kj for the following gas phase reaction: CFCl3 + HF ==> CF2Cl2 + HCl given the following bond energies in kj/mol: C-F 485, H-F 565, C-Cl 331, H-Cl 431 a) +20kJ b) -20kJ c) -180kJ d) +288kJ 28. The electron configuration of the S ion is. a) [Ne]3s 2 3p 6 b) [Ar]3s 2 3p 2 c) [Ar]3s 2 3p 6 d) [Ne]3s 2 3p 2 29. Bond enthalpy is. a) sometimes positive, sometimes negative b) always negative c) always positive d) unpredictable 3

30. The Cl-Si-Cl bond angle in the SiCl 2F 2 molecule is approximately. a) 109.5 b) 90 c) 120 d) 180 31. The blending of one s atomic orbital and two p atomic orbitals produces. a) three sp3 hybrid orbitals b) three sp hybrid orbitals c) two sp3 hybrid orbitals d) three sp2 hybrid orbitals 32. The molecular geometry of the left-most carbon atom in the molecule below is. a) T-shaped b) octahedral c) trigonal bipyramidal d) tetrahedral Consider the following species when answering the question #33: (i) PCl3 (ii) CCl4 (iii) TeCl4 (iv) XeF4 (v) SF6 33. In which of the molecules does the central atom utilize d orbitals to form hybrid orbitals? a) (i) and (ii) b) (iii) only c) (iii), (iv), and (v) d) (v) only 34. The molecular geometry of the CHF 3 molecule is, and the molecule is. a) trigonal pyramidal, polar b) seesaw, polar c) tetrahedral, polar d) tetrahedral, nonpolar 35. The electron-domain geometry and the molecular geometry of a molecule of the general formula ABn will always be the same if. a) n is greater than four b) there is more than one central atom c) n is less than four d) there are no lone pairs on the central atom 36. The hybridizations of iodine in IF 3 and IF 5 are and, respectively. a) sp 3 d 2, sp 3 d b) sp 3 d, sp 3 d 2 c) sp 3, sp 3 d d) sp 3 d 2, sp 3 d 2 37. The F-B-F bond angle in the BF 3 molecule is. a) 90 b) 120 c) 180 d) 109.5 38. The electron-domain geometry of the AsF 6-1 ion is octahedral. The hybrid orbitals used by the As atom for bonding are orbitals. a) sp 3 b) sp 3 d c) sp 3 d 2 d) sp 2 d 2 39. There are σ and π bonds in the HNC== CNH molecule. a) 8 and 3 b) 5 and 3 c) 4 and 3 d) 3 and 4 4

40. The F-N-F bond angle in the NF 3 molecule is slightly less than. a) 90 b) 120 c) 180 d) 109.5 41. According to valence bond theory, which orbitals on bromine atoms overlap in the formation of the bond in Br 2? a) 4p b) 3p c) 4s d) 3s For the questions that follow, consider the BEST Lewis structures of the following oxyanions: (i) NO 2 - (ii) NO 3 - (iii) SO 3 (iv) SO 4 (v) BrO 3-42. There can be four equivalent best resonance structures of. a) i b) ii c) iii d) iv 43. Of the molecules below, the bond in is the most polar. a) H 2 b) HI c) HF d) HCl 44. A valid Lewis structure of cannot be drawn without violating the octet rule. a) SbF 3 b) IF 3 c) NF 3 d) PF 3 45. The chloride of which of the following metals should have the greatest lattice energy? a) K b) Rb c) Cs d) Li 46. Why don't we draw double bonds between the Be atom and the Cl atoms in BeCl 2? a) That would result in the formal charges not adding up to zero. b) There aren't enough electrons. c) That would result in more than eight electrons around each chlorine atom. d) That would give positive formal charges to the chlorine atoms and a negative formal charge to the beryllium atom 47. Using the table of bond dissociation energies, the ΔH for the following reaction is kj. 2HCl (g) + F2 (g)---- 2HF (g) + Cl2 (g) a) +223kJ b) -359kJ c) +208kJ d) -223kJ 48. How many unpaired electrons are there on the central atom in the Lewis structure of a N 3- ion? a) 0 b) 1 c) 2 d) 3 49. A nonpolar bond will form between two atoms of electronegativity. a) similar, different b) identical, equal c) different, opposite d) different, different 50. The image below depicts a T-shaped structure (looking down on the axial atom). Which of the following has such a structure? a) SO 3 b) BCl 3 c) ICl 3 d) PCl 3 5

51. How many bonds are there in a triple bond? a) 1 b) 2 c) 3 d) 4 52. What is the proper order of increasing Cl A Cl angle? A) SCl 2 B) PCl 3 C) SiCl 4 a) C < A < B b) A < B < C c) B < C < A d) A < C < B e) C < B < A 53. Are the following molecules polar? (i) (ii) a) Only i is polar. b) Neither is polar. c) Both i and ii are polar. d) Only ii is polar. 54. The fact that the BF 3 molecule is planar means that the B atom is a) sp 2 -hybridized. b) sp-hybridized. c) unhybridized. d) sp 3 -hybridized. 55. The N-N bonding in HNNH consists of a) one bond and two bonds. b) one bond and no bonds. c) two bond and one bonds. d) two bond and two bonds. e) one bond and one bonds. 56. Which molecule has a nitrogen atom with sp 2 hybridization? a) acetonitrile, CH 3C N: b) trimethylamine, :N(CH 3) 3 c) nitromethane, CH 3NO 2 d) ammonium cation, NH 4 + 57. Which of the following shapes is not possible for a molecule in which the central atom has sp 3 d hybridization? a) tetrahedral b) seesaw c) T-shaped d) linear 58. SiF 6 exists, but CF 6 does not. Why? Use the concept of hybrid orbitals in your answer. a) Carbon sp 3 cannot accommodate six ligands (attached atoms). b) Carbon is never found in ions. c) Silicon is less electronegative, so its hybrid orbitals are lower in energy. d) Silicon can hybridize using d orbitals not available in carbon. 59. Are bonds generally stronger or weaker than bonds? Why? a) Weaker. There is less electron density between the atoms. b) Stronger. There is less electron density between the atoms. c) Weaker. There is more electron density between the atoms. d) Stronger. There is more electron density between the atoms. 6

60. Consider the Lewis structure for glycine, the simplest amino acid: What is the total number of bonds in the entire molecule, and what is the total number of bonds? a) 8 bonds and two bonds b) 7 bonds and one bond c) 9 bonds and one bond d) 14 bonds and one bond 61. The valence shell electron pair repulsion (VSEPR) theory is based on the idea that a) nonbonded electron domains require more space than bonded electron pairs. b) the electron domains about an atom arrange themselves in such a fashion as to maximize the interaction between each domain. c) the electron domains arrange themselves in such a fashion as to minimize the interaction between each domain. d) nonbonded electron domains require less space than bonded electron domains. e) the relative bond lengths in molecules determine the shape of the molecules. 62. Two isomeric forms of a organic molecule a) have the same structure. b) have different compositions of elements. c) have the same molecular formula. d) have a different content of the isotopes of hydrogen. 63. Which of the following is the correct Lewis dash formula for carbon diselenide? 64. How many unshared pairs of electrons are in the outer shell of the central nitrogen atom of NH3? a. 4 b. 3 c. 2 d. 1 e. 0 65. The number of unshared pairs of electrons in the outer shell of oxygen in Cl 2O is. a. one b. two c. three d. four e. zero 66. Which Lewis Dot Formula below is incorrect? 67. The valence shell is a. the highest energy level occupied by electrons. b. the set of orbitals used to make triple bonds. c. the orbitals belonging to the entire molecule. d. the lowest energy level occupied by electrons. e. the hard covering on crustaceans. 7

68. The phosphorus pentachloride molecule is nonpolar and contains no lone (unshared) electron pairs on the phosphorus atom. What are all of the possible Cl-P-Cl bond angles? a. 120 b. 180 c. 109.5 d. 90, 120, and 180 e. 90 and 180 69. Which of the following statements about the valence bond theory is false? a. For an atom to share more than 8 electrons it must hybridize d orbitals. b. To make 4 single bonds, an atom will make 4 sp3 hybrid orbitals. c. The number of hybrid orbitals formed equals the number of high electron density regions. d. Trigonal planar molecules use sp2 hybrid orbitals e. Atoms that do not complete their octet use either sp3d or sp3d2 hybrid orbitals. 70. The hybridization associated with the central atom of a molecule in which all the bond angles are 120 is. a. sp b. sp2 c. sp3 d. sp3d e. sp3d2 71. Which of the following molecules has 120 bond angles? a. BF 4 - b. CF 4 c. H 2O d. BI 3 e. NH 4 + 72. Which of the following statements about molecules with octahedral electronic geometry is false? a. They are sp3d2 hybridized. b. The molecular geometry is square planar if there are two lone pairs of electrons on the central atom. c. The bond angles are 90, 120 or 180. d. Octahedral geometry is symmetrical. e. If there are two lone pairs of electrons on the central atom they will be 180 apart. 73. How many sigma (σ) bonds and how many pi (π) bonds does the ethane (C 2H 2) molecule contain? a. 4 σ, 2 π b. 5 σ, 2 π c. 5 σ, 1 π d. 5 σ, 0 π e. 8 σ, 2 π 74. Which molecule is incorrectly matched with the molecular geometry? a. SF 6 = octahedral b. AsH 3 = pyramidal c. BCl 3 = trigonal planar d. AsF 5 = trigonal bipyramidal e. H 2S = linear 75. Which species is incorrectly matched with the hybridization at the central atom? a. SO 2 = sp2 b. CF 4 = sp3 c. PF 5 = sp3d2 d. SeO 4 = sp3 e. HCN = sp 8

76. Which species is incorrectly matched with bond angles? a. SiCl 4 = 109.5 b. BeI 2 = slightly less than 109 c. SF 6 = 90 (and 180 ) d. AsF 5 = 90, 120 (and 180 ) e. BF 3 = 120 77. Which one of the following is a nonpolar molecule with polar bonds? a. H 2O b. NH 3 c. PF 5 d. CHCl 3 e. none of these 78. Which set of hybridization states of C1, C2, and N of the following molecule is correct? a. C1 = sp 2, C2 = sp 3, N = sp 3 b. C1 = sp 2, C2 = sp 2, N = sp 3 c. C1 = sp 2, C2 = sp 2, N = sp 2 d. C1 = sp 2, C2 = sp 3, N = sp 2 79. Which set of hybridization states of C1, C2, and N of the following molecule is correct? a. C1 = sp 2, C2 = sp 3, N = sp 3 b. C1 = sp 3, C2 = sp 2, N = sp 3 c. C1 = sp 3, C2 = sp 2, N = sp 2 d. C1 = sp 2, C2 = sp 2, N = sp 3 9