Electronegativity, Fajan's rule, dipole moment, VSEPR theory, hybridization, resonance, valence bond theory and molecular orbital concepts - Question Bank

1. According to Fajan's rules, the bond between Li+ and Cl- is more covalent than the bond between K+ and Cl- because:
A) Li+ has a larger ionic radius than K+
B) Li+ has a higher charge density than K+
C) K+ has a higher polarizing power than Li+
D) Cl- is larger than Li+
2. The electronegativity value of an element is highest when:
A) It has a large atomic radius and low nuclear charge
B) It has a small atomic radius and high effective nuclear charge
C) It has many electron shells and low effective nuclear charge
D) It is an alkali metal
3. Which of the following molecular orbitals has the highest energy?
A) Bonding sigma (σ) molecular orbital
B) Antibonding sigma (σ*) molecular orbital
C) Bonding pi (π) molecular orbital
D) Antibonding pi (π*) molecular orbital
4. Valence Bond Theory considers a covalent bond as a result of:
A) Complete electron transfer
B) Partial sharing of electrons
C) Resonance stabilization
D) Delocalization of electrons
5. Resonance structures of a molecule have:
A) Different arrangements of atoms
B) Different numbers of electrons
C) Same arrangement of atoms but different distribution of electrons
D) Different bond orders
6. The hybridization of the central carbon atom in ethyne (acetylene, C2H2) is:
A) sp
B) sp2
C) sp3
D) s2p
7. According to VSEPR theory, the molecular geometry of SO2 is:
A) Linear
B) Trigonal planar
C) Bent (V-shaped)
D) Tetrahedral
8. Which of the following molecules is polar?
A) CH4
B) CCl4
C) CHCl3
D) CO2
9. Fajan's rules are used to predict the degree of covalent character in:
A) Purely ionic compounds
B) Purely covalent compounds
C) Ionic compounds
D) Metallic compounds
10. Which of the following factors increases atomic radius, thereby decreasing electronegativity?
A) Increase in nuclear charge
B) Decrease in shielding effect
C) Addition of electron shells
D) Increase in effective nuclear charge
11. The bond order of He2 molecule according to MOT is:
A) 0
B) 1
C) 2
D) 0.5
12. Pi (π) bonds are formed by the:
A) Head-on overlap of atomic orbitals
B) Sideways overlap of atomic orbitals
C) Overlap of s-orbitals
D) Overlap of hybrid orbitals
13. Which of the following is a valid resonance structure for carbonate ion (CO3^2-)?
A) A structure with all C-O single bonds.
B) A structure with one C=O double bond and two C-O single bonds, with charges distributed.
C) A structure with three C=O double bonds.
D) A structure with alternating single and double bonds around the carbon.
14. The hybridization of the central sulfur atom in SF6 is:
A) sp3
B) sp3d
C) sp3d2
D) sp2d
15. According to VSEPR theory, what is the molecular geometry of PCl5?
A) Tetrahedral
B) Trigonal bipyramidal
C) Octahedral
D) Square pyramidal
16. The net dipole moment of a molecule depends on:
A) Individual bond moments
B) Molecular geometry
C) Both individual bond moments and molecular geometry
D) The number of atoms in the molecule
17. Which of the following compounds exhibits the highest covalent character according to Fajan's rules?
A) MgO
B) NaCl
C) AlCl3
D) CsI
18. The order of electronegativity of halogens is:
A) F > Cl > Br > I
B) I > Br > Cl > F
C) Cl > F > Br > I
D) F > Br > Cl > I
19. Which of the following diatomic molecules is paramagnetic according to MOT?
A) N2
B) O2
C) CO
D) F2
20. Sigma (σ) bonds are formed by the overlap of orbitals along the:
A) Inter-nuclear axis
B) Perpendicular axis to the inter-nuclear axis
C) Equatorial plane
D) Axial plane
21. The delocalization of pi electrons in conjugated systems is best described by:
A) Valence Bond Theory
B) Resonance
C) VSEPR Theory
D) Hybridization
22. What is the hybridization of the central boron atom in BCl3?
A) sp
B) sp2
C) sp3
D) d-sp3
23. In VSEPR theory, a molecule with a central atom bonded to five other atoms and no lone pairs has which electron geometry?
A) Tetrahedral
B) Trigonal bipyramidal
C) Octahedral
D) Square planar
24. The dipole moment of CO2 is zero because:
A) It is a nonpolar molecule
B) The bond moments of C=O bonds cancel each other due to linear geometry
C) Carbon and oxygen have similar electronegativities
D) The C-O bonds are purely covalent
25. According to Fajan's rules, a large positive charge on the cation leads to:
A) Decreased polarization
B) Increased polarization
C) No change in polarization
D) Formation of ionic bond
26. Which of the following is NOT a factor affecting electronegativity?
A) Nuclear charge
B) Atomic radius
C) Number of neutrons
D) Electron configuration
27. In MOT, antibonding molecular orbitals are denoted by an asterisk (*) and have:
A) Lower energy than parent atomic orbitals
B) Higher energy than parent atomic orbitals
C) Equal energy to parent atomic orbitals
D) No energy difference from parent atomic orbitals
28. Valence Bond Theory explains the formation of sigma (σ) bonds through:
A) Sideways overlap of p-orbitals
B) Head-on overlap of atomic orbitals
C) Overlap of s-orbitals with p-orbitals
D) Overlap of d-orbitals
29. Benzene (C6H6) is a classic example of a molecule exhibiting:
A) Isomerism
B) Resonance
C) Tautomerism
D) Allotropy
30. What is the hybridization of the central oxygen atom in water (H2O)?
A) sp
B) sp2
C) sp3
D) s2p
31. According to VSEPR theory, the electron geometry and molecular geometry are the same when:
A) There are lone pairs on the central atom
B) There are no lone pairs on the central atom
C) The molecule is linear
D) The molecule is planar
32. The dipole moment of NH3 is non-zero due to:
A) The presence of lone pair on nitrogen and pyramidal shape
B) The presence of double bonds
C) The symmetrical arrangement of hydrogen atoms
D) The high electronegativity of hydrogen
33. Which of the following will have the highest percentage of ionic character?
A) NaCl
B) KCl
C) RbCl
D) CsCl
34. Electronegativity is the measure of the tendency of an atom to:
A) Donate electrons
B) Attract shared electrons
C) Lose protons
D) Gain neutrons
35. The bond order of a diatomic molecule 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
36. According to Valence Bond Theory, a covalent bond is formed by:
A) The attraction between oppositely charged ions
B) The sharing of electrons between atoms
C) The overlap of atomic orbitals
D) The formation of a mobile electron sea
37. Which of the following species exhibits resonance?
A) CH4
B) CO2
C) O3 (Ozone)
D) H2O
38. The hybridization of the central atom in BF3 is:
A) sp
B) sp2
C) sp3
D) d2sp3
39. What is the bond angle in a molecule with trigonal planar electron geometry and no lone pairs on the central atom?
A) 90 degrees
B) 109.5 degrees
C) 120 degrees
D) 180 degrees
40. A molecule with a positive dipole moment is considered:
A) Nonpolar
B) Polar
C) Ionic
D) Metallic
41. Fajan's rule states that polarization of an anion by a cation is favored by:
A) High charge on cation, large cation
B) Low charge on cation, small cation
C) High charge on anion, small anion
D) Low charge on anion, large anion
42. Which factor significantly influences electronegativity differences, leading to polar covalent bonds?
A) Atomic radius
B) Nuclear charge
C) Number of valence electrons
D) All of the above
43. In Molecular Orbital Theory (MOT), when atomic orbitals combine, they form:
A) Only bonding molecular orbitals
B) Only antibonding molecular orbitals
C) Bonding and antibonding molecular orbitals
D) Hybrid orbitals
44. Valence Bond Theory (VBT) primarily explains chemical bonding based on:
A) Delocalized electrons
B) Orbital overlap
C) Molecular orbital formation
D) Electron repulsion
45. Resonance is a phenomenon observed in molecules where:
A) Electrons are completely localized
B) Bond lengths are intermediate between single and double bonds
C) There is a complete transfer of electrons
D) The molecule exists in a single, fixed structure
46. What is the hybridization of the central carbon atom in methane (CH4)?
A) sp
B) sp2
C) sp3
D) dsp2
47. According to VSEPR theory, what is the electron geometry of a molecule with two lone pairs and two bonding pairs around the central atom?
A) Linear
B) Trigonal planar
C) Tetrahedral
D) Bent (or V-shaped)
48. The dipole moment of which molecule is zero?
A) H2O
B) NH3
C) CO2
D) HCl
49. According to Fajan's rules, the covalent character of an ionic bond increases with:
A) Larger cation and smaller anion
B) Smaller cation and larger anion
C) Larger cation and larger anion
D) Smaller cation and smaller anion
50. Which of the following elements is the most electronegative?
A) Carbon
B) Nitrogen
C) Oxygen
D) Fluorine
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