NEET 2025 MCQ with Answer Explanation : “Molecular Orbital Theory”.

41. Which of the following is an example of a homonuclear diatomic molecule?
A) CO
B) HCl
C) N2
D) NaCl
Answer: C

Explanation: N2 is a homonuclear diatomic molecule because it consists of two atoms of the same element.

42. How do bonding molecular orbitals affect the stability of a molecule?
A) They destabilize the molecule.
B) They have no effect on stability.
C) They stabilize the molecule.
D) They only affect ionic bonds.
Answer: C

Explanation: Bonding molecular orbitals lower the overall energy of the system, stabilizing the molecule.

43. Which molecule has a higher bond order than CO?
A) O2
B) N2
C) B2
D) H2
Answer: B

Explanation: N2 has a bond order of 3, which is higher than CO’s bond order of 2.

44. Which molecular orbital is filled first in a molecular orbital diagram?
A) σ*2s
B) π2p
C) σ2p
D) σ2s
Answer: D

Explanation: According to the Aufbau principle, the lowest energy orbitals are filled first, so σ2s is filled before π2p.

45. What is the primary reason for the bonding in a diatomic molecule?
A) Presence of lone pairs
B) Atomic size
C) Overlap of atomic orbitals
D) Electronegativity difference
Answer: C

Explanation: The overlap of atomic orbitals forms bonding molecular orbitals, leading to the formation of the molecule.

46. In a molecular orbital diagram, where would you find the antibonding orbitals?
A) Above the bonding orbitals
B) Below the bonding orbitals
C) At the same level as bonding orbitals
D) In a separate energy level
Answer: A

Explanation: Antibonding orbitals are always higher in energy than their corresponding bonding orbitals.

47. Which of the following species has the lowest bond energy?
A) F2
B) O2
C) N2
D) H2

Answer: A

Explanation: F2 has a single bond which is weaker than the double and triple bonds present in O2 and N2, leading to lower bond energy.

48. In the molecular orbital theory, what is meant by “degenerate” orbitals?
A) Orbitals that have different energies
B) Orbitals that have the same energy
C) Orbitals that cannot hold electrons
D) Orbitals that are non-bonding

Answer: B

Explanation: Degenerate orbitals have the same energy level, which is important for filling orbitals in accordance with Hund’s Rule.

49. Which molecule has a bond angle of approximately 120°?
A) H2O
B) NH3
C) BCl3
D) CH4

Answer: C

Explanation: BCl3 has a trigonal planar geometry, leading to bond angles of approximately 120°.

50. What is the hybridization of the central atom in CH4?
A) sp
B) sp²
C) sp³
D) dsp²

Answer: C

Explanation: The central carbon atom in CH4 undergoes sp³ hybridization to form four equivalent bonds.