51. Which molecular orbital is characterized by having a nodal plane between the two nuclei?
A) σ2s
B) π2p
C) σ2s D) π2p
Answer: C
Explanation: The σ*2s orbital has a nodal plane between the two nuclei, indicating destructive interference in the bonding.
52. What happens to the bond order if one electron is added to an antibonding molecular orbital?
A) It increases
B) It decreases
C) It stays the same
D) It becomes zero
Answer: B
Explanation: Adding an electron to an antibonding orbital reduces the bond order, weakening the bond.
53. Which molecular species is expected to have the shortest bond length?
A) O2
B) N2
C) H2
D) F2
Answer: B
Explanation: N2 has a triple bond, which results in a shorter bond length compared to O2 and H2.
54. What type of overlap is required for the formation of a sigma bond?
A) Side-to-side
B) End-to-end
C) Random
D) None
Answer: B
Explanation: Sigma bonds are formed by the end-to-end overlap of atomic orbitals, resulting in a strong bond.
55. In a molecular orbital diagram, how many total orbitals are formed from four atomic orbitals?
A) 2
B) 3
C) 4
D) 8
Answer: C
Explanation: The combination of four atomic orbitals produces four molecular orbitals (two bonding and two antibonding).
56. Which of the following molecules would you expect to have a bond angle of approximately 109.5°?
A) H2O
B) CH4
C) NH3
D) SO2
Answer: B
Explanation: CH4 has a tetrahedral shape with bond angles of about 109.5° due to sp³ hybridization.
57. Which of the following statements is true about the 2p molecular orbitals?
A) They have a spherical shape.
B) They are formed by the overlap of s orbitals.
C) They can form both bonding and antibonding orbitals.
D) They have only one nodal plane.
Answer: C
Explanation: 2p orbitals can form both bonding (π) and antibonding (π*) molecular orbitals through their lateral overlap.
58. Which type of bonding is primarily responsible for the structure of diamond?
A) Ionic bonding
B) Metallic bonding
C) Covalent bonding
D) Hydrogen bonding
Answer: C
Explanation: Diamond has a tetrahedral structure formed by strong covalent bonds between carbon atoms.
59. What is the molecular shape of SF6?
A) Octahedral
B) Tetrahedral
C) Trigonal planar
D) Linear
Answer: A
Explanation: SF6 has an octahedral molecular geometry due to sp³d² hybridization of the central sulfur atom.
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