Questions on Valence Bond Theory
Multiple-Choice Questions: Valence Bond Theory
1. What does the Valence Bond (VB) Theory primarily explain?
A) Atomic number of elements
B) Color of compounds
C) Geometry and bonding in molecules
D) Radioactivity in atoms
E) Solubility of ionic substances
2. According to VB theory, a covalent bond forms when:
A) Two nuclei fuse together
B) Electrons are transferred between atoms
C) Orbitals of two atoms overlap
D) Atoms share neutrons
E) One atom becomes an ion
3. Which type of orbital overlap results in a sigma (σ) bond?
A) Side-by-side overlap of p orbitals
B) End-to-end overlap of orbitals
C) Overlap of d orbitals only
D) Interaction between nuclei
E) No overlap at all
4. A pi (π) bond results from:
A) End-to-end overlap of s orbitals
B) Side-to-side overlap of parallel p orbitals
C) Sharing of electrons in d orbitals
D) Overlap of two s orbitals
E) Attraction between two nuclei
5. Which of the following bonds is the strongest according to VB theory?
A) Pi bond
B) Sigma bond
C) Ionic bond
D) Metallic bond
E) Dispersion force
6. In a double bond, how many bonds are sigma and how many are pi?
A) 2 sigma, 0 pi
B) 1 sigma, 1 pi
C) 0 sigma, 2 pi
D) 2 sigma, 1 pi
E) 1 sigma, 2 pi
7. The hybridization of the central atom in CH₄ is:
A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²
8. Which hybrid orbitals are used by carbon in C₂H₄ (ethene)?
A) sp³
B) sp²
C) sp
D) sp³d
E) d²sp³
9. Which of the following involves sp hybridization?
A) H₂O
B) NH₃
C) C₂H₂ (ethyne)
D) CO₂
E) Both C and D
10. Which statement is true according to VB theory?
A) All orbitals have the same shape
B) Atoms combine when they lose electrons
C) Bonds form when orbitals of two atoms overlap and electrons are shared
D) Electrons are always in circular orbits
E) All molecules are linear
11. In VB theory, overlapping orbitals must have:
A) The same shape
B) Electrons with opposite spins
C) Only s-orbital character
D) Identical energy
E) Electrons from the same atom
12. Which molecule has sp² hybridization at the central atom?
A) H₂O
B) BF₃
C) CH₄
D) C₂H₆
E) NH₃
13. Which geometry is associated with sp³ hybridization?
A) Linear
B) Trigonal planar
C) Tetrahedral
D) Trigonal bipyramidal
E) Octahedral
14. Which of the following has linear geometry due to sp hybridization?
A) BeCl₂
B) H₂O
C) NH₃
D) CH₄
E) COCl₂
15. The concept of hybridization is used in VB theory to explain:
A) Color of molecules
B) Atomic mass
C) Molecular shape and bond angles
D) Ionization energy
E) Electron affinity
16. The sp³d hybridization corresponds to which geometry?
A) Tetrahedral
B) Trigonal bipyramidal
C) Trigonal planar
D) Linear
E) Octahedral
17. Which element in PCl₅ exhibits sp³d hybridization?
A) P
B) Cl
C) All atoms
D) Only outer atoms
E) None
18. What type of bond exists between carbon atoms in ethyne (C₂H₂)?
A) One sigma, one pi
B) One sigma, two pi
C) Two sigma, one pi
D) Two sigma, two pi
E) Only pi bonds
19. Which molecule has three sigma bonds and one lone pair on the central atom?
A) CH₄
B) BF₃
C) NH₃
D) BeCl₂
E) CO₂
20. Which statement best describes a sigma bond?
A) Weaker than pi bond
B) Does not involve orbital overlap
C) Formed by side-to-side overlap
D) Formed by head-on overlap of orbitals
E) Found only in double bonds
Answers with Explanations
1. C) VB theory explains bonding and geometry of molecules.
2. C) A covalent bond is formed when atomic orbitals overlap.
3. B) Sigma bonds are formed by end-to-end (head-on) orbital overlap.
4. B) Pi bonds are formed by side-by-side overlap of p orbitals.
5. B) Sigma bonds are stronger than pi bonds due to better orbital overlap.
6. B) A double bond has 1 sigma and 1 pi bond.
7. C) CH₄ has sp³ hybridization (tetrahedral shape).
8. B) In C₂H₄, carbon is sp² hybridized (double bond present).
9. E) Both C₂H₂ and CO₂ have sp hybridization.
10. C) Bonds form when orbitals overlap and electrons are shared.
11. B) The overlapping orbitals must have electrons with opposite spins.
12. B) BF₃ has sp² hybridization (trigonal planar).
13. C) sp³ hybridization → tetrahedral geometry.
14. A) BeCl₂ is linear, showing sp hybridization.
15. C) Hybridization explains molecular shape and bond angles.
16. B) sp³d hybridization → trigonal bipyramidal geometry.
17. A) The central atom P in PCl₅ is sp³d hybridized.
18. B) C₂H₂ has 1 sigma and 2 pi bonds (a triple bond).
19. C) NH₃ has 3 sigma bonds and 1 lone pair on nitrogen.
20. D) Sigma bonds are formed by head-on overlap of orbitals.
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