Questions: Resonance (Chemical)
Questions: Resonance (Chemical Bonding)
1. What is resonance in chemistry?
A) Rapid vibration of electrons
B) Movement of protons in a molecule
C) Delocalization of electrons across multiple atoms
D) Formation of ionic bonds
E) Vibration of molecules due to heat
2. Which of the following best describes a resonance structure?
A) A molecule with unpaired electrons
B) A molecule with broken bonds
C) A different possible Lewis structure of the same molecule
D) An isomer of the original compound
E) A hybrid orbital
3. Resonance structures differ only in:
A) Atom positions
B) Nuclear arrangements
C) Electron positions
D) Atomic numbers
E) Molecular mass
4. Which of the following molecules exhibits resonance?
A) CH₄
B) H₂O
C) NH₃
D) CO₃²⁻
E) HCl
5. In a resonance hybrid, the true structure of the molecule is:
A) One of the resonance forms
B) An average of all resonance forms
C) The one with the most atoms
D) The most symmetrical form
E) The most polar form
6. Which ion exhibits resonance by having equivalent bond lengths between atoms?
A) OH⁻
B) NO₃⁻
C) NH₄⁺
D) Na⁺
E) H₂S
7. What is the purpose of drawing resonance structures?
A) To show bond angles
B) To indicate ionic bonding
C) To represent delocalized electrons
D) To display molar mass
E) To illustrate phase changes
8. Which molecule shows resonance involving a carbon-oxygen double bond?
A) CH₄
B) CO₃²⁻
C) H₂O
D) NH₃
E) CH₃OH
9. Which of the following is not a valid resonance contributor?
A) One with incomplete octet on carbon
B) One obeying the octet rule
C) One minimizing formal charge
D) One maximizing charge separation
E) One that has delocalized electrons
10. Which of these is true about resonance structures?
A) They rapidly convert between forms in solution
B) Only the most stable structure contributes
C) Electrons are localized in each form
D) They are a theoretical representation of delocalization
E) They occur only in gases
11. Which of these molecules has exactly three resonance structures?
A) NO₃⁻
B) NH₄⁺
C) CO₂
D) H₂O
E) HF
12. Which of the following is the best resonance structure?
A) The one with the most charges
B) The one that places negative charge on the least electronegative atom
C) The one with incomplete octets
D) The one with minimal formal charge and complete octets
E) The one with the most double bonds
13. Which of the following compounds shows resonance due to delocalized π electrons?
A) Ethane
B) Benzene
C) Methanol
D) Hydrogen peroxide
E) Sodium chloride
14. In benzene, the delocalized electrons form:
A) Ionic bonds
B) Sigma bonds
C) Circular π-bond cloud
D) Coordinate covalent bonds
E) Localized dipoles
15. Why is benzene more stable than expected?
A) It is nonpolar
B) It has no lone pairs
C) It exhibits resonance
D) It is saturated
E) It forms hydrogen bonds
16. Which of the following resonance contributors would be least significant?
A) One with all atoms having complete octets
B) One with formal charges minimized
C) One with like charges on adjacent atoms
D) One where electronegative atoms bear negative charges
E) One with neutral atoms and full octets
17. What is a key feature of all valid resonance structures?
A) They show different atomic arrangements
B) They differ only in sigma bonds
C) They obey the same number of electrons
D) They show different numbers of electrons
E) They represent different compounds
18. How does resonance affect bond length in molecules like CO₃²⁻?
A) It makes one bond much longer
B) It causes random bond lengths
C) It equalizes bond lengths between atoms
D) It removes double bonds entirely
E) It increases the ionic character
19. Which type of bonding allows for resonance structures?
A) Sigma bonding only
B) Ionic bonding only
C) π (pi) bonding
D) Metallic bonding
E) Hydrogen bonding
20. Resonance typically occurs when:
A) Only sigma bonds are present
B) Molecules are linear
C) Electrons can be delocalized in π systems or lone pairs
D) Atoms are highly electronegative
E) There are no double bonds
- Questions on Molecular Compounds
- Questions on Lewis Electron-Dot Structures
- Questions on Covalent Bonding in Polyatomic Ions
Answers with Full Explanations
1. C) Resonance is electron delocalization across two or more atoms.
2. C) Resonance structures are alternative Lewis structures for the same molecule.
3. C) Only the position of electrons differs in resonance structures.
4. D) CO₃²⁻ (carbonate) exhibits resonance among its three oxygen atoms.
5. B) The actual molecule is a hybrid or average of all resonance forms.
6. B) NO₃⁻ has three equivalent N–O bond lengths due to resonance.
7. C) Resonance structures show delocalized electrons not localized in one bond.
8. B) CO₃²⁻ contains resonance with C=O and C–O bonds.
9. D) Structures with large charge separation are less stable and less valid.
10. D) Resonance is a conceptual tool to represent delocalization.
11. A) NO₃⁻ has three resonance structures.
12. D) The best resonance contributor has minimal formal charge and complete octets.
13. B) Benzene has delocalized π electrons over a ring.
14. C) Benzene has a circular π electron cloud.
15. C) Resonance stabilizes benzene, making it less reactive.
16. C) Like charges on adjacent atoms are highly unfavorable.
17. C) All valid structures must use the same number of electrons.
18. C) Resonance causes equal bond lengths between atoms (e.g., in CO₃²⁻).
19. C) Resonance occurs with π bonding (and sometimes lone pairs).
20. C) Resonance requires delocalized electrons, typically in π systems or lone pairs.
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