JEE Main - Valence bond theory resonance and molecular orbital theory basics Online Test (MCQ Quiz)

1. Which of the following statements is NOT true regarding Valence Bond Theory (VBT)?

A) VBT considers the overlap of atomic orbitals to form covalent bonds. B) VBT explains bond formation through the sharing of electrons between overlapping orbitals. C) VBT effectively explains the magnetic properties of molecules like O2. D) VBT describes the delocalization of electrons over multiple atoms.

2. In Valence Bond Theory, a covalent bond is formed when atomic orbitals overlap.

A) Partially filled atomic orbitals overlap to form a sigma bond. B) Half-filled atomic orbitals overlap to form a sigma or pi bond. C) Completely filled atomic orbitals overlap to form a sigma bond. D) Empty atomic orbitals overlap to form a pi bond.

3. What is the primary difference between sigma (σ) and pi (π) bonds in VBT?

A) Sigma bonds are formed by the lateral overlap of p-orbitals, while pi bonds are formed by the head-on overlap of s-orbitals. B) Sigma bonds involve end-to-end overlap of orbitals and are stronger than pi bonds, which involve side-by-side overlap. C) Pi bonds are formed by the overlap of hybrid orbitals, while sigma bonds are formed by the overlap of pure atomic orbitals. D) Sigma bonds are always formed between two identical atoms, whereas pi bonds can be formed between different atoms.

4. Hybridization in Valence Bond Theory is a concept used to explain:

A) The delocalization of electrons in aromatic compounds. B) The geometry and equivalent bonding of molecules. C) The formation of coordinate covalent bonds. D) The existence of resonance structures.

5. Which type of hybridization is associated with a trigonal planar geometry?

A) sp B) sp2 C) sp3 D) dsp2

6. The hybridization of the central atom in methane (CH4) is:

A) sp B) sp2 C) sp3 D) d2sp3

7. According to VBT, the molecule BCl3 has:

A) sp3 hybridization and trigonal pyramidal geometry. B) sp2 hybridization and trigonal planar geometry. C) sp hybridization and linear geometry. D) sp3d hybridization and see-saw geometry.

8. Which of the following is a key limitation of Valence Bond Theory?

A) It cannot explain the formation of single bonds. B) It fails to accurately predict bond lengths. C) It does not adequately explain the magnetic properties of some molecules, like O2. D) It overestimates the stability of molecules.

9. Resonance is a concept used to describe:

A) The complete transfer of electrons between atoms. B) The averaging of bond lengths and electron distribution in certain molecules or ions. C) The formation of pi bonds through lateral overlap. D) The hybridization of atomic orbitals.

10. Which of the following species exhibits resonance?

A) H2O B) CO2 C) O3 (Ozone) D) CH4

11. In the resonance structures of carbonate ion (CO3^2-), how many resonance structures are possible?

A) 1 B) 2 C) 3 D) 4

12. The actual structure of a molecule exhibiting resonance is:

A) An average of the contributing resonance structures. B) Identical to one of the contributing resonance structures. C) A rapidly oscillating state between the resonance structures. D) A linear combination of all possible resonance structures.

13. Which of the following is a characteristic of resonance structures?

A) They differ in the arrangement of atoms. B) They differ only in the distribution of electrons. C) They have different total charges. D) They have different numbers of valence electrons.

14. The stability of a molecule exhibiting resonance is generally:

A) Lower than any of its contributing resonance structures. B) Higher than any of its contributing resonance structures. C) Equal to the average energy of its contributing resonance structures. D) Dependent on the number of pi electrons.

15. Benzene (C6H6) is a classic example of a molecule exhibiting resonance. Its resonance structures show:

A) Alternating single and double bonds. B) Equal bond lengths between all carbon atoms. C) Localized double bonds. D) One Kekulé structure.

16. Molecular Orbital Theory (MOT) differs from VBT and Lewis theory by:

A) Considering atomic orbitals as indivisible units. B) Treating electrons as localized between two atoms. C) Describing molecular orbitals formed from the combination of all atomic orbitals of the constituent atoms. D) Focusing solely on hybridization.

17. In MOT, when atomic orbitals combine, they form:

A) Only bonding molecular orbitals. B) Only antibonding molecular orbitals. C) Both bonding and antibonding molecular orbitals. D) Hybrid molecular orbitals.

18. Bonding molecular orbitals are formed by the constructive interference of atomic orbitals and have:

A) Higher energy than the parent atomic orbitals. B) Lower energy than the parent atomic orbitals. C) The same energy as the parent atomic orbitals. D) No definite energy level.

19. Antibonding molecular orbitals are formed by the destructive interference of atomic orbitals and possess:

A) A node between the nuclei. B) Increased electron density between the nuclei. C) Lower energy than the parent atomic orbitals. D) Greater stability than bonding molecular orbitals.

20. The bond order in MOT is calculated as:

A) (Number of bonding electrons - Number of antibonding electrons) / 2 B) (Number of antibonding electrons - Number of bonding electrons) / 2 C) Number of bonding electrons + Number of antibonding electrons D) Number of bonding electrons / Number of antibonding electrons

21. A bond order of zero in MOT indicates:

A) A very strong bond. B) A stable molecule. C) The molecule does not exist. D) A coordinate covalent bond.

22. According to MOT, the oxygen molecule (O2) is:

A) Diamagnetic with a bond order of 2. B) Paramagnetic with a bond order of 2. C) Diamagnetic with a bond order of 1. D) Paramagnetic with a bond order of 1.

23. Which of the following molecular orbitals is formed by the end-to-end overlap of atomic orbitals?

A) Sigma (σ) molecular orbital B) Pi (π) molecular orbital C) Delta (δ) molecular orbital D) F-molecular orbital

24. Which of the following molecular orbitals is formed by the lateral overlap of atomic orbitals?

A) Sigma (σ) molecular orbital B) Pi (π) molecular orbital C) Hybrid molecular orbital D) Atomic molecular orbital

25. In the molecular orbital diagram of N2, the order of filling molecular orbitals is:

A) σ1s, σ*1s, σ2s, σ*2s, π2px, π2py, σ2pz, π*2px, π*2py, σ*2pz B) σ1s, σ*1s, σ2s, σ*2s, σ2pz, π2px, π2py, π*2px, π*2py, σ*2pz C) σ1s, σ2s, σ*1s, σ*2s, π2px, π2py, σ2pz, π*2px, π*2py, σ*2pz D) σ1s, σ*1s, π2px, π2py, σ2s, σ*2s, σ2pz, π*2px, π*2py, σ*2pz

26. The bond order of He2 molecule, according to MOT, is:

A) 0 B) 1 C) 0.5 D) 2

27. Which of the following diatomic molecules is paramagnetic according to MOT?

A) N2 B) F2 C) O2 D) CO

28. The number of sigma bonds in a single bond is:

A) 1 B) 0 C) 2 D) Depends on the atoms involved

29. A double bond consists of:

A) One sigma bond and one pi bond. B) Two sigma bonds. C) Two pi bonds. D) One sigma bond and two pi bonds.

30. A triple bond consists of:

A) One sigma bond and two pi bonds. B) Three sigma bonds. C) Two sigma bonds and one pi bond. D) Three pi bonds.

31. Which hybridization scheme leads to linear geometry?

A) sp B) sp2 C) sp3 D) d2sp3

32. In the context of resonance, the delocalization of electrons leads to:

A) Increased reactivity. B) Decreased stability. C) Increased stability. D) No change in stability.

33. Which of the following is an example of a resonance hybrid?

A) A single Lewis structure. B) An intermediate structure that averages properties of contributing structures. C) A hypothetical structure. D) The most stable contributing structure.

34. The concept of hybridization in VBT helps explain:

A) The exact positions of electrons in a molecule. B) The bond angles and shapes of molecules. C) The overall energy of the molecule. D) The magnetic properties of molecules.

35. Which atomic orbitals overlap to form a sigma (σ) bond between two p-orbitals?

A) Head-on overlap B) Lateral overlap C) End-to-end overlap D) Side-by-side overlap

36. The formation of a pi (π) bond involves:

A) End-to-end overlap of atomic orbitals. B) Lateral overlap of atomic orbitals. C) Hybridization of s and p orbitals. D) Overlap of only s orbitals.

37. According to MOT, the bond order of O2+ is:

A) 1.5 B) 2.0 C) 2.5 D) 3.0

38. According to MOT, the bond order of O2- is:

A) 1.0 B) 1.5 C) 2.0 D) 2.5

39. Which theory best explains the paramagnetism of oxygen (O2)?

A) Valence Bond Theory B) Lewis Theory C) Molecular Orbital Theory D) VSEPR Theory

40. In resonance, the contributing structures are:

A) Real, observable forms of the molecule. B) Hypothetical structures that cannot be isolated. C) Different isomers of the molecule. D) All equivalent and equally contribute to the hybrid.

41. The energy difference between the resonance hybrid and the most stable contributing resonance structure is called:

A) Activation energy B) Resonance energy C) Bonding energy D) Ionization energy

42. Which of the following molecule has sp3 hybridization?

A) BeCl2 B) BF3 C) C2H2 D) C2H6 (Ethane)

43. In the molecule H2O, the oxygen atom is hybridized as:

A) sp B) sp2 C) sp3 D) No hybridization

44. The number of pi electrons in benzene (C6H6) is:

A) 6 B) 12 C) 3 D) 9

45. Which of the following is a bonding molecular orbital?

A) σ* B) π* C) σ D) p

46. Which of the following is an antibonding molecular orbital?

A) σ B) π C) σ* D) s

47. The bond order of Li2 molecule, according to MOT, is:

A) 0 B) 1 C) 0.5 D) 2

48. In VBT, the overlap of atomic orbitals is responsible for:

A) Electron delocalization B) Bond formation C) Resonance D) Molecular orbital formation

49. Which of the following pairs of atomic orbitals can form a pi (π) bond through lateral overlap?

A) 1s and 1s B) 2s and 2s C) 2pz and 2pz D) 1s and 2pz

50. According to MOT, the molecule B2 is:

A) Diamagnetic with bond order 1 B) Paramagnetic with bond order 1 C) Diamagnetic with bond order 0 D) Paramagnetic with bond order 2

Valence bond theory resonance and molecular orbital theory basics - Online Test

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