Resonance – Daily Practice Paper (DPP)
NEET & JEE Main + Advanced Level
1. [NEET 2024]
Which of the following has the highest number of resonating structures?
(A) CO₃²⁻ (B) SO₃ (C) NO₃⁻ (D) Both (A) and (C) show equal resonance
Which of the following has the highest number of resonating structures?
(A) CO₃²⁻ (B) SO₃ (C) NO₃⁻ (D) Both (A) and (C) show equal resonance
Correct Answer: (D)
All three have three equivalent resonance structures. CO₃²⁻ and NO₃⁻ both have identical resonance hybrids.
All three have three equivalent resonance structures. CO₃²⁻ and NO₃⁻ both have identical resonance hybrids.
2. [JEE Advanced 2023]
The total number of canonical structures that can be drawn for the nitrosonium ion (NO⁺) is:
(A) 2 (B) 3 (C) 4 (D) 0
The total number of canonical structures that can be drawn for the nitrosonium ion (NO⁺) is:
(A) 2 (B) 3 (C) 4 (D) 0
Correct Answer: (A)
⁺N≡O ↔ N=O⁺ (both are equally contributing)
⁺N≡O ↔ N=O⁺ (both are equally contributing)
3. [NEET 2023]
The correct order of acid strength is:
(A) CH₃COOH > C₆H₅OH > H₂CO₃ > C₂H₅OH
(B) C₆H₅OH > H₂CO₃ > C₂H₅OH > CH₃COOH
(C) C₆H₅OH > CH₃COOH > H₂CO₃ > C₂H₅OH
(D) H₂CO₃ > CH₃COOH > C₆H₅OH > C₂H₅OH
The correct order of acid strength is:
(A) CH₃COOH > C₆H₅OH > H₂CO₃ > C₂H₅OH
(B) C₆H₅OH > H₂CO₃ > C₂H₅OH > CH₃COOH
(C) C₆H₅OH > CH₃COOH > H₂CO₃ > C₂H₅OH
(D) H₂CO₃ > CH₃COOH > C₆H₅OH > C₂H₅OH
Correct Answer: (A)
Resonance stabilization of conjugate base:
CH₃COO⁻ (2 equiv. structures) > C₆H₅O⁻ (4 structures) > HCO₃⁻ > C₂H₅O⁻ (no resonance)
Resonance stabilization of conjugate base:
CH₃COO⁻ (2 equiv. structures) > C₆H₅O⁻ (4 structures) > HCO₃⁻ > C₂H₅O⁻ (no resonance)
4. [JEE Main 2024]
Major resonance contributor of vinyl carbocation H₂C=CH–CH₂⁺ is:
(A) H₂C–CH=CH₂⁺ (B) ⁺CH₂–CH=CH₂ (C) Both equally contribute
Major resonance contributor of vinyl carbocation H₂C=CH–CH₂⁺ is:
(A) H₂C–CH=CH₂⁺ (B) ⁺CH₂–CH=CH₂ (C) Both equally contribute
Correct Answer: (C)
Both are equivalent → allylic carbocation, highly stable
Both are equivalent → allylic carbocation, highly stable
5. [JEE Advanced 2022]
Among the following, the most stable resonance structure is:
(A) CH₂=CH–Cl (B) CH₂–CH=Cl⁺ (C) ⁺CH₂–CH=Cl (D) CH₂=CH–Cl⁻
Among the following, the most stable resonance structure is:
(A) CH₂=CH–Cl (B) CH₂–CH=Cl⁺ (C) ⁺CH₂–CH=Cl (D) CH₂=CH–Cl⁻
Correct Answer: (A)
Neutral molecule with complete octet is always most stable. No charge separation.
Neutral molecule with complete octet is always most stable. No charge separation.
6. [NEET 2025 Pattern]
The total number of resonance structures for phenoxide ion (C₆H₅O⁻) in which negative charge appears on ring carbon is:
The total number of resonance structures for phenoxide ion (C₆H₅O⁻) in which negative charge appears on ring carbon is:
4 (two ortho + one para + one meta minor, but only 3 major structures place charge on carbon)
7. In which of the following molecules is resonance NOT possible?
(A) CH₂=CH–CHO (B) CH₂=CH–CH=CH₂ (C) CH₃–CH₂–OH (D) CH₂=CH–CH₂⁻
(A) CH₂=CH–CHO (B) CH₂=CH–CH=CH₂ (C) CH₃–CH₂–OH (D) CH₂=CH–CH₂⁻
Correct Answer: (C)
Ethanol has no π bonds or lone pairs adjacent to each other.
Ethanol has no π bonds or lone pairs adjacent to each other.
8. [JEE Main 2023]
The bond order of C–O bond in carboxylate ion (RCOO⁻) is:
(A) 1 (B) 2 (C) 1.5 (D) 1.33
The bond order of C–O bond in carboxylate ion (RCOO⁻) is:
(A) 1 (B) 2 (C) 1.5 (D) 1.33
Correct Answer: (C)
1.5 (two equivalent resonance structures)
1.5 (two equivalent resonance structures)
9. [JEE Advanced 2021]
Which carbocation is most stabilized by resonance?
(A) (C₆H₅)₃C⁺ (B) (C₆H₅)₂CH⁺ (C) C₆H₅CH₂⁺ (D) CH₃CH₂CH₂⁺
Which carbocation is most stabilized by resonance?
(A) (C₆H₅)₃C⁺ (B) (C₆H₅)₂CH⁺ (C) C₆H₅CH₂⁺ (D) CH₃CH₂CH₂⁺
Correct Answer: (A)
Triphenylmethyl cation → 9+ significant resonance structures
Triphenylmethyl cation → 9+ significant resonance structures
10. The correct decreasing order of resonance energy is:
(A) Benzene > Pyridine > Pyrrole > Thiophene
(B) Benzene > Thiophene > Pyrrole > Pyridine
(C) Benzene > Pyrrole > Pyridine > Thiophene
(D) Pyrrole > Pyridine > Thiophene > Benzene
(A) Benzene > Pyridine > Pyrrole > Thiophene
(B) Benzene > Thiophene > Pyrrole > Pyridine
(C) Benzene > Pyrrole > Pyridine > Thiophene
(D) Pyrrole > Pyridine > Thiophene > Benzene
Correct Answer: (B)
Benzene > Thiophene > Pyrrole > Pyridine
Benzene > Thiophene > Pyrrole > Pyridine
| Compound | Resonance Energy (kJ/mol) |
Reason (brief) |
|---|---|---|
| Benzene | 150–155 | Perfect 6π-electron aromatic system, maximum stabilization |
| Thiophene | 120–130 | Highly aromatic (sulfur 2 lone pairs contribute effectively) |
| Pyrrole | 90–105 | Aromatic, but N–H forces partial lone-pair involvement → less stabilization |
| Pyridine | 110–120 | Aromatic, but electronegative N distorts electron density → least among these |
11. Total resonance structures for ozone (O₃):
(A) 1 (B) 1.5 (C) 2 (D) 3
(A) 1 (B) 1.5 (C) 2 (D) 3
Correct Answer: (C)
2 major
2 major
12. [NEET 2022]
Which has maximum resonance energy?
(A) Benzene (B) Naphthalene (C) Anthracene (D) Phenanthrene
Which has maximum resonance energy?
(A) Benzene (B) Naphthalene (C) Anthracene (D) Phenanthrene
Correct Answer: (A)
Benzene
Benzene
| Compound | No. of fused rings | Total Resonance Energy (kJ/mol) |
Resonance Energy per ring (kJ/mol) |
|---|---|---|---|
| Benzene | 1 | 150–155 | 150–155 |
| Naphthalene | 2 | 255–260 | ~128 |
| Anthracene | 3 | 350–360 | ~118 |
| Phenanthrene | 3 | 380–390 | ~128 |
13. The most stable resonating structure of acrolein (CH₂=CH–CHO) is:
(A) CH₂–CH=CH–O⁻ (B) ⁺CH₂–CH=CH–OH (C) Both contribute equally
(A) CH₂–CH=CH–O⁻ (B) ⁺CH₂–CH=CH–OH (C) Both contribute equally
Correct Answer: (C)
Push-pull effect – both important
Push-pull effect – both important
14. Nitrobenzene has how many significant resonance structures?
(A) 3 (B) 5 (C) 6 (D) 7
(A) 3 (B) 5 (C) 6 (D) 7
Correct Answer: (D)
7 (1 non-charged + 6 charged in ring)
7 (1 non-charged + 6 charged in ring)
15. [JEE Main 2025 Pattern]
The number of electrons in the delocalized π-system of tropone is:
(A) 2 (B) 3 (C) 4 (D) 6
The number of electrons in the delocalized π-system of tropone is:
(A) 2 (B) 3 (C) 4 (D) 6
Correct Answer: (D)
6π (aromatic)
6π (aromatic)
16. Which is the least contributing resonance structure of phenol?
(A) With –O⁻ and +ve on ortho carbon (B) With quinoid structure on meta carbon
(A) With –O⁻ and +ve on ortho carbon (B) With quinoid structure on meta carbon
Correct Answer: (B)
Meta-quinoid is least stable and least contributing because:
Meta-quinoid is least stable and least contributing because:
- The oxygen lone pair cannot effectively delocalize the positive charge to the meta position through resonance (meta directing effect is not favored by +R groups like –OH or –O⁻).
- It violates the natural ortho–para directing tendency of the phenoxide oxygen.
- It has higher energy and does not benefit from the same level of stabilization as the ortho and para forms.
17. In which ion are all bonds equal?
(A) NO₃⁻ (B) CO₃²⁻ (C) Both (D) None
(A) NO₃⁻ (B) CO₃²⁻ (C) Both (D) None
Correct Answer: (C)
Both have 3 equivalent resonance structures
Both have 3 equivalent resonance structures
18. Which has no resonance?
(A) Graphite (B) Diamond (C) Benzene (D) Fullerene
(A) Graphite (B) Diamond (C) Benzene (D) Fullerene
Correct Answer: (B)
Diamond – sp³, no delocalization
Diamond – sp³, no delocalization
19. Enolate of acetone has how many resonance structures?
(A) 0 (B) 1 (C) 2 (D) 3
(A) 0 (B) 1 (C) 2 (D) 3
Correct Answer: (C)
2
2
20. The bond order of N–O in nitro group (–NO₂) is:
(A) 1 (B) 1.5 (C) 2 (D) 2.25
(A) 1 (B) 1.5 (C) 2 (D) 2.25
Correct Answer: (B)
1.5
1.5
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