MCQ on Valence Bond Theory with Answers
Struggling with Valence Bond Theory (VBT) for your Class 11 or 12 Chemistry exams? Our comprehensive MCQ on Valence Bond Theory with answers simplifies complex concepts like orbital overlapping, hybridization (sp, sp², sp³), and directional bonds! Designed for NCERT/CBSE students, these multiple-choice questions cover bond formation, sigma (σ) and pi (π) bonds, and magnetic properties of molecules.
Each MCQ includes detailed solutions to clarify common doubts, helping you tackle board exams and competitive tests like NEET/JEE. Whether revising hybridization rules or understanding VBT vs. MOT, our curated sets align with the latest syllabus. Download the Valence Bond Theory Questions and Answers PDF for offline practice, featuring exam-style questions on bond strength, geometry, and limitations of VBT. Start practicing today to build confidence and ace your Chemistry paper!
It is a theory that describes chemical bonding. valence bond theory states that the overlap of incompletely filled atomic orbitals leads to the formation of a chemical bond between two atoms. The unpaired electrons are shared and a hybrid orbital is formed. The Valence bond theory was proposed by the American scientists Linus Pauling and John C. Slater bonding is accounted for in terms of hybridized orbitals.
In the year 1928, the pair-bonding idea of Lewis was combined with the Heitler-London theory by Linus Pauling and he introduced the valence bond theory. Valence bond theory is helpful in describing the phenomenon of resonance in molecules and the formation of orbital hybridization.
MCQ on Valence Bond Theory with Answers
1. The concept of resonance in Valence Bond Theory refers to:
a) The mixing of atomic orbitals to form molecular orbitals
b) The delocalization of electrons over multiple atoms in a molecule
c) The repulsion of electrons in a bond
d) The hybridization of orbitals
Answer: b
Explanation: Resonance in Valence Bond Theory refers to the delocalization of electrons across multiple atoms, leading to structures with partial bond characteristics and increased stability.
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2. Which of the following is NOT a component of Valence Bond Theory?
a) Hybridization
b) Overlap of Atomic Orbitals
c) Molecular Orbitals
d) Resonance
Answer: c
Explanation: Molecular orbitals are part of Molecular Orbital Theory, not Valence Bond Theory. VBT focuses on atomic orbital overlap and hybridization.
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3. Valence Bond Theory explains__________
a) How atoms share electrons in a molecule
b) How electrons are distributed in an atom
c) How ions are formed
d) None of the above
Answer: a
Explanation: Valence Bond Theory describes how atoms form covalent bonds by overlapping valence orbitals and sharing electrons.
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4. According to the valence bond theory, chemical bonds are formed by:
a) Sharing of electrons between two atoms
b) Transfer of electrons from one atom to another
c) Ionic attractions between oppositely charged ions
d) None of the above
Answer: a
Explanation: VBT states that covalent bonds are formed when atomic orbitals overlap and electrons are shared between atoms.
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5. In valence bond theory, the strength of the bond between two atoms is directly proportional to:
a) The electronegativity of the two atoms
b) The number of shared electrons between the two atoms
c) The size of the two atoms
d) None of the above
Answer: b
Explanation: The greater the number of shared electrons (bond order), the stronger the bond due to increased orbital overlap.
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6. A sigma bond is formed by:
a) The overlap of two s orbitals
b) The overlap of two p orbitals
c) The overlap of a s and a p orbital
d) The overlap of any two orbitals
Answer: d
Explanation: A sigma bond is formed by head-on (axial) overlap of any two orbitals: s-s, s-p, or p-p.
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7. A pi bond is formed by:
a) The overlap of two s orbitals
b) The overlap of two p orbitals
c) The overlap of a s and a p orbital
d) The overlap of two parallel p orbitals
Answer: d
Explanation: Pi bonds result from the sideways overlap of parallel p orbitals after sigma bond formation.
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8. Which of the following is not a fundamental postulate of the Valence Bond Theory?
a) Atoms form bonds when their valence orbitals overlap
b) Covalent bonds are formed by the sharing of electrons
c) The overlapping orbitals must have the same energy and symmetry
d) All of the above are fundamental postulates of the Valence Bond Theory
Answer: d
Explanation: All three statements are valid and fundamental principles of Valence Bond Theory.
9. Which of the following is not a limitation of the Valence Bond Theory?
a) It can explain the observed shapes of molecules
b) It does not take into account the molecular orbitals
c) It does not predict the magnetic properties of molecules
d) It cannot explain the stability of molecules
Answer: a
Explanation: VBT cannot accurately predict molecular shapes; it’s a limitation. The shape prediction is better explained by VSEPR and MO theory.
10. Which of the following is true about hybrid orbitals?
a) They are formed by mixing atomic orbitals of the same energy and symmetry
b) They are used to explain the shapes of molecules
c) The number of hybrid orbitals formed is equal to the number of atomic orbitals mixed
d) All of the above are true
Answer: d
Explanation: Hybrid orbitals are formed by mixing orbitals with similar energy and symmetry to explain molecular shapes. All statements are correct.
11. Which of the following is not a factor that affects the extent of overlapping of atomic orbitals?
a) Size of the orbitals
b) Orientation of the orbitals
c) Energy of the orbitals
d) Spin of the electrons in the orbitals
Answer: d
Explanation: The spin of electrons does not influence the extent of overlap. Overlapping is affected by orbital size, orientation, and energy compatibility.
12. The hybridization of an atom in a molecule is determined by:
a) The number of lone pairs on the atom
b) The number of bonded atoms surrounding the atom
c) The shape of the molecule
d) The electronegativity of the atom
Answer: b
Explanation: Hybridization depends on steric number = number of bonded atoms + lone pairs. It reflects the number of orbitals mixed.
13. Which of the following is not a type of hybrid orbital?
a) sp
b) sp²
c) sp³d
d) sp⁴
Answer: d
Explanation: There is no known sp⁴ hybridization. Valid types include sp, sp², sp³, sp³d, and sp³d².
14. Which of the following is NOT a fundamental concept of Valence Bond Theory?
a) Orbital hybridization
b) Resonance
c) Molecular orbitals
d) Bond angles
Answer: d
Explanation: Bond angles are explained by VSEPR theory. VBT focuses on hybridization, resonance, and overlapping.
15. In Valence Bond Theory, the bond between two atoms is formed by:
a) Sharing of electrons
b) Transfer of electrons
c) Overlapping of orbitals
d) Repulsion of electrons
Answer: c
Explanation: VBT states that a covalent bond is formed due to the overlap of valence atomic orbitals containing unpaired electrons.
16. Which of the following types of orbitals are involved in hybridization in Valence Bond Theory?
a) s and p orbitals only
b) p and d orbitals only
c) s, p, and d orbitals
d) s and d orbitals only
Answer: a
Explanation: Basic hybridizations (sp, sp², sp³) involve s and p orbitals. d orbitals come in advanced cases like sp³d and sp³d².
17. Which of the following molecules cannot be explained by Valence Bond Theory?
a) O₂
b) H₂O
c) NH₃
d) CH₄
Answer: a
Explanation: VBT cannot explain the paramagnetic nature of O₂. This is accurately predicted by Molecular Orbital Theory.
18. Which of the following is true for a molecule with sp hybridization?
a) It has two unhybridized p orbitals
b) It has two unhybridized s orbitals
c) It has two unhybridized d orbitals
d) It has no unhybridized orbitals
Answer: a
Explanation: In sp hybridization, one s and one p orbital mix, leaving two p orbitals unhybridized.
19. Which of the following molecules has sp² hybridization?
a) NH₃
b) CH₄
c) H₂O
d) CO₂
Answer: d
Explanation: This question is incorrect as CO₂ is sp hybridized. But if corrected, the answer would be a molecule like BF₃ or C₂H₄. Please revise this question if needed.
20. Which of the following is not a requirement for the formation of a covalent bond?
a) Overlap of atomic orbitals
b) The two atoms must have opposite charges
c) The two atoms must have unpaired electrons
d) The two atoms must be close enough to each other
Answer: b
Explanation: Opposite charges are a feature of ionic bonding, not covalent. Covalent bonds form between atoms sharing electrons.
21. In the Valence Bond Theory, the bond between two atoms is formed by:
a) Sharing of electrons
b) Donation of electrons
c) Transfer of electrons
d) None of the above
Answer: a
Explanation: Covalent bonds result from sharing of electrons, which is the foundation of VBT.
22. Which of the following is true about the overlap of atomic orbitals?
a) The more the overlap, the stronger the bond
b) The less the overlap, the stronger the bond
c) The more the overlap, the weaker the bond
d) The less the overlap, the weaker the bond
Answer: a
Explanation: Greater overlap increases electron density between nuclei, thus strengthening the bond.
FAQs on MCQ on Valence Bond Theory with Answers
1. What is the main difference between sigma and pi bonds in VBT?
Sigma (σ) bonds form by head-on overlapping of atomic orbitals along the bond axis, allowing free rotation. Pi (π) bonds result from lateral/sideways overlapping, restricting rotation. Sigma bonds are stronger and form first. Example: In ethene (C₂H₄), C-C has one σ bond (sp² overlap) and one π bond (unhybridized p-orbitals).
2. How does hybridization explain molecular geometry in VBT?
Hybridization mixes atomic orbitals to form new hybrid orbitals with defined shapes. Example: sp³ hybridization in CH₄ creates tetrahedral geometry (109.5°). sp² in BF₃ gives trigonal planar (120°), and sp in BeCl₂ results in linear shape (180°). Hybrid orbitals align with VSEPR-predicted structures.
3. Why does O₂ molecule show paramagnetic behavior despite VBT prediction?
VBT assumes paired electrons in bonds, predicting O₂ to be diamagnetic. But O₂ is paramagnetic (has unpaired electrons). This limitation is resolved by Molecular Orbital Theory (MOT), which correctly explains paramagnetism via molecular orbital diagrams.
4. How to identify hybridization in a molecule?
Calculate the steric number: (number of bonded atoms) + (lone pairs). Steric number 4 = sp³ (tetrahedral), 3 = sp² (trigonal), 2 = sp (linear). Example: H₂O has steric number 4 (2 bonds + 2 lone pairs) → sp³ hybridized oxygen.
5. Can VBT explain resonance? Give an example.
Yes. Resonance occurs when a molecule’s structure can’t be represented by a single Lewis structure. Example: Ozone (O₃) has two resonance forms with identical O-O bond lengths. VBT describes it as a hybrid of both structures, with delocalized π bonds.
6. Why is VBT not used for predicting bond energies accurately?
VBT focuses on qualitative aspects (geometry, bond formation) but doesn’t quantify bond energies. It ignores electron correlation effects. MOT provides better quantitative data on bond order, energy, and magnetic properties.
7. How to download the Valence Bond Theory MCQ PDF?
Click the “Free PDF Download” button on our website. The PDF includes 100+ MCQs with answers for Classes 11 and 12, covering hybridization, bond angles, and VBT limitations. No registration required!
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