TRB PG Assistant - Molecular orbital theory for diatomic and simple triatomic molecules One Line Questions & Answers

1. In the molecular orbital diagram of Be₂, the electrons fill up to which set of molecular orbitals? — (σ₂s)² (σ*₂s)²

2. According to MOT, what is the electronic configuration of the ground state of B₂? — (σ₂s)² (σ*₂s)² (π₂p)²

3. The bond order of B₂ is 1. What is the correct molecular orbital configuration for B₂? — (σ₂s)² (σ*₂s)² (π₂p)²

4. In the MOT diagram of H₂, how many electrons are present in the bonding σ molecular orbital? — 2

5. What is the bond order of H₂ according to MOT? — 1

6. In the MOT diagram of He₂, how many electrons occupy the antibonding σ* molecular orbital? — 2

7. What is the calculated bond order for He₂ using MOT? — 0

8. What is the bond order of Li₂? — 1

9. What is the number of unpaired electrons in O₂ according to MOT? — 2

10. The molecule F₂ has the molecular orbital configuration (σ₂s)² (σ*₂s)² (σ₂p)² (π₂p)⁴ (π*₂p)⁴. What is its bond order? — 1

11. What is the bond order of the diatomic molecule B₂? — 1

12. What is the bond order of O₂? — 2.5

13. What is the bond order of N₂? — 3

14. What is the bond order of CO based on its molecular orbital configuration? — 3

15. What is the bond order of the O₂⁻ ion? — 2.5

16. In the molecular orbital diagram of O₂, the π*₂p orbitals are filled with how many electrons? — 4

17. Consider the diatomic molecule CO. Which atomic orbitals are primarily involved in forming the σ molecular orbitals? — 2s and 2p orbitals of Carbon and Oxygen

18. The spectral transition responsible for the color of a substance is related to the energy difference between: — The HOMO and LUMO.

19. In the formation of π bonding molecular orbitals from p-orbitals, the electron density is concentrated: — Above and below the internuclear axis.

20. What type of molecular orbitals are formed when atomic orbitals combine in-phase (constructive interference)? — Bonding molecular orbitals

21. According to Molecular Orbital Theory (MOT), what is the fundamental difference between atomic orbitals and molecular orbitals? — Atomic orbitals are associated with individual atoms, while molecular orbitals are delocalized over the entire molecule.

22. What is the primary condition for the linear combination of atomic orbitals (LCAO) to form molecular orbitals? — Atomic orbitals must have the same symmetry and comparable energies.

23. Which of the following diatomic molecules is diamagnetic? — N₂

24. Which of the following is NOT a type of molecular orbital formed from the combination of atomic orbitals? — Hybrid molecular orbital

25. When are π molecular orbitals formed in diatomic molecules? — By the sideways overlap of p orbitals.

26. For a molecule like CO, which atom's atomic orbitals contribute more significantly to the lower energy molecular orbitals? — Oxygen (more electronegative)

27. Which diatomic molecule is predicted to be paramagnetic by MOT but is observed to be diamagnetic? — He₂

28. Which of the following is a characteristic of a bonding molecular orbital? — It has lower energy than the parent atomic orbitals.

29. Which statement best describes the bonding in NO according to MOT? — It is paramagnetic with a bond order of 2.5.

30. Which of the following diatomic molecules has the highest bond order? — C₂

31. The molecule O₂⁺ has one less electron than O₂. How does this affect its bond order and stability compared to O₂? — Higher bond order, more stable

32. What is the characteristic feature of an antibonding molecular orbital compared to a bonding molecular orbital? — Higher energy and decreased electron density between nuclei

33. Which diatomic molecule is expected to be the most stable based on bond order? — N₂

34. Which of the following species would be expected to be paramagnetic? — O₂⁻

35. Which of the following correctly orders the bond strength of diatomic molecules according to MOT? — N₂ > O₂ > F₂

36. What does a bond order of 1 indicate for a diatomic molecule? — A single covalent bond exists between the atoms.

37. Which of the following diatomic ions has a bond order of 3? — C₂²⁻

38. When two atomic orbitals combine to form molecular orbitals, how many molecular orbitals are formed? — Two

39. Which of the following best describes the molecular orbitals formed from the combination of two 2p atomic orbitals oriented end-to-end? — One σ bonding and one σ antibonding orbital

40. The energy difference between bonding and antibonding molecular orbitals is generally: — Smaller than the energy difference between the original atomic orbitals.

41. According to MOT, diatomic molecules with a bond order of zero are: — Unstable and do not exist

42. What is the primary reason for the existence of homonuclear diatomic molecules of elements from Li to N showing s-p mixing? — Close energy proximity of 2s and 2p atomic orbitals.

43. The molecular orbital diagram for heteronuclear diatomic molecules like CO is similar to homonuclear ones, but with a key difference in orbital energies. What is this difference? — The atomic orbitals of the more electronegative atom are lower in energy.

44. For diatomic molecules from O₂ to Ne₂, the energy order of molecular orbitals is different from Li₂ to N₂. Which statement correctly describes this difference? — The σ₂p orbital is lower in energy than the π₂p orbitals.

45. In the context of MOT, what is the significance of the number of electrons in antibonding molecular orbitals? — They decrease bond strength.

46. The molecular orbital configuration of Li₂ is (σ₂s)² (σ*₂s)² (σ₂p)². — False

47. What is the primary advantage of using MOT over Valence Bond Theory (VBT) for explaining the properties of molecules? — MOT can explain paramagnetism and diamagnetism of molecules.

48. Which symbol is used to denote an antibonding molecular orbital formed from s orbitals? — σ*

49. The HOMO (Highest Occupied Molecular Orbital) of N₂ is: — σ₂p

50. The LUMO (Lowest Unoccupied Molecular Orbital) of O₂ is: — π*₂p

Molecular orbital theory for diatomic and simple triatomic molecules - One Line Questions