“Valence Bond Theory” MCQ with Answer Explanation : NEET 2025.

51. The bond angle in a molecule of XeF₂ is:
    A. 90°
    B. 109.5°
    C. 180°
    D. 120°

Answer: C. 180°

Explanation: In xenon difluoride (XeF₂), xenon is sp³d hybridized, and the molecule has a linear shape with a bond angle of 180°.

52. According to VBT, lone pairs of electrons on the central atom:
    A. Do not affect molecular geometry
    B. Increase bond angles
    C. Repel bonding pairs and reduce bond angles
    D. Are involved in sigma bonds

Answer: C. Repel bonding pairs and reduce bond angles

Explanation: Lone pairs on the central atom repel bonding pairs, which leads to a reduction in bond angles. This explains why the bond angle in molecules like H₂O is less than the ideal tetrahedral angle of 109.5°.

53. In a trigonal bipyramidal molecule, the bond angles are:
    A. 90° and 180°
    B. 90° and 120°
    C. 109.5°
    D. 120° and 180°

Answer: B. 90° and 120°

Explanation: In a trigonal bipyramidal structure, like PCl₅, the bond angles are 90° between axial and equatorial positions and 120° between the equatorial positions.

54. In VBT, hybrid orbitals are:
    A. Lower in energy than the original orbitals
    B. Higher in energy than the original orbitals
    C. Equivalent in energy to the original orbitals
    D. Averaged energy between the original orbitals

Answer: D. Averaged energy between the original orbitals

Explanation: Hybrid orbitals have an energy level that is an average of the original atomic orbitals that combined to form them.

55. The shape of NH₃ can be explained using which type of hybridization?
    A. sp
    B. sp²
    C. sp³
    D. sp³d

Answer: C. sp³

Explanation: In ammonia (NH₃), nitrogen undergoes sp³ hybridization, which results in a trigonal pyramidal shape due to the lone pair on nitrogen.

56. Which of the following molecules exhibits sp hybridization?
    A. C₂H₄
    B. CH₄
    C. CO₂
    D. NH₃

Answer: C. CO₂

Explanation: In carbon dioxide (CO₂), the central carbon atom undergoes sp hybridization, resulting in a linear geometry with bond angles of 180°.

57. In Valence Bond Theory, bond strength increases with:
    A. Less overlap of atomic orbitals
    B. Greater overlap of atomic orbitals
    C. More lone pairs on the central atom
    D. The number of pi bonds

Answer: B. Greater overlap of atomic orbitals

Explanation: In VBT, stronger bonds result from greater overlap of atomic orbitals, as this leads to a higher degree of electron sharing between atoms.

58. Which of the following statements is true about a pi bond?
    A. It forms by head-on overlap of atomic orbitals
    B. It is weaker than a sigma bond
    C. It is always the first bond to form between two atoms
    D. It involves hybrid orbitals

Answer: B. It is weaker than a sigma bond

Explanation: A pi bond is generally weaker than a sigma bond because it results from the side-to-side overlap of p-orbitals, which is less effective than the head-on overlap in a sigma bond.

59. In VSEPR theory, the presence of lone pairs on the central atom:
    A. Does not affect the shape
    B. Affects only the bond length
    C. Changes the bond angles
    D. Only affects molecules with pi bonds

Answer: C. Changes the bond angles

Explanation: According to VSEPR theory, lone pairs on the central atom exert more repulsion than bonding pairs, which leads to a change in bond angles, often reducing them.

60. Which of the following molecules has a square planar shape?
    A. NH₃
    B. XeF₄
    C. BF₃
    D. H₂O

Answer: B. XeF₄

Explanation: Xenon in xenon tetrafluoride (XeF₄) is sp³d² hybridized, resulting in a square planar shape due to the presence of two lone pairs.