Sample Questions - Chapter 9

Molecular Orbital Theory

Examples of
Multiple Choice Questions

1.: Which statement is false? A sigma molecular orbital; (a) may result from overlap of p atomic orbitals perpendicular to the molecular axis (side-on).; (b) may result from overlap of p atomic orbitals along the molecular axis (head-on).; (c) may result from overlap of two s atomic orbitals.; (d) may result from overlap of one s and one p atomic orbitals.; (e) may be either bonding or antibonding.
2.: Carbon monoxide has ten bonding electrons and four antibonding electrons. Therefore it has a bond order of; (a) 3; (b) 7; (c) 1; (d) 5/2; (e) 2
3.: Which of the following is the correct electron configuration for C₂?; (a) _1s² _2s² _2py² *_1s² *_2s² *_2py²; (b) _1s² *_1s² _2s² *_2s² _2py² *_2pz¹ _2p¹; (c) _1s² *_1s² _2s² *_2s² _2py² _2pz²; (d) _1s² *_1s² _2s² *_2s² _2py¹ _2pz¹; (e) _1s² *_1s² _2s² *_2s² _2py¹ *_2py¹ _2pz¹ *_2pz¹
4.: What is the correct electron configuration for the molecular ion, B₂⁺?; (a) _1s² *_1s² _2s² *_2s² _2p²; (b) _1s² *_1s² _2s² *_2s² _2py²; (c) _1s² *_1s² _2s² *_2s² _2py² _2pz¹; (d) _1s² *_1s² _2s² *_2s² _2p¹ _2py¹; (e) none of the above.
5.: Draw the molecular orbital diagram for the molecular ion, N₂⁺. The number of electrons in the _2p molecular orbital is:; (a) 0; (b) 1; (c) 2; (d) 3; (e) 4
6.: What is the bond order in O₂⁺?; (a) 3.5; (b) 2.0; (c) 1.5; (d) 2.5; (e) 0
7.: Draw the molecular orbital diagram for B₂. The number of unpaired electrons in the B₂ molecule is _____.; (a) zero; (b) 1; (c) 2; (d) 3; (e) 4
8.: Which one of the following statements is false?; (a) Valence bond theory and molecular orbital theory can be described as two different views of the same thing.; (b) When one considers the molecular orbitals resulting from the overlap of any two specific atomic orbitals, the bonding orbitals are always lower in energy than the antibonding orbitals.; (c) Molecular orbitals are generally described as being more delocalized than hybridized atomic orbitals.; (d) One of the shortcomings of molecular orbital theory is its inability to account for a triple bond in the nitrogen molecule, N₂.; (e) One of the shortcomings of valence bond theory is its inability to account for the paramagnetism of the oxygen molecule, O₂.
9.: Antibonding molecular orbitals are produced by; (a) constructive interaction of atomic orbitals.; (b) destructive interaction of atomic orbitals.; (c) the overlap of the atomic orbitals of two negative ions; (d) all of these; (e) none of these
10.: Which statement regarding stable heteronuclear diatomic molecules is false?; (a) All have bond orders greater than zero.; (b) The antibonding molecular orbitals have more of the character of the more electropositive element than of the more electronegative element.; (c) Their molecular orbital diagrams are more symmetrical than those of homonuclear diatomic molecules.; (d) The bonding molecular orbitals have more of the character of the more electronegative element than of the less electronegative element.; (e) The greater is the difference in energy between two overlapping atomic orbitals, the more polar the resulting bond is, due to electrons occupying the resulting bonding molecular orbital.

Answers:

1. (a) 2. (a) 3. (c) 4. (e) 5. (b) 6. (d) 7. (c) 8. (d) 9. (b) 10. (c)

To report any corrections, please e-mail Dr. Wendy Keeney-Kennicutt.