Electronic effects inductive electromeric resonance and hyperconjugation - Question Bank

1. Which of the following statements about hyperconjugation is FALSE?
A) It is also known as no-bond resonance.
B) It involves the delocalization of sigma electrons.
C) It requires the presence of an unsaturated system.
D) It stabilizes carbocations and alkenes.
2. The relative stability of species like carbocations, carbanions, and radicals is primarily determined by:
A) Only the inductive effect
B) Only resonance
C) Inductive effect, resonance, and hyperconjugation
D) Electromeric effect and steric effects
3. Which effect is responsible for the difference in reactivity between ethene and ethane towards electrophiles?
A) Inductive effect
B) Electromeric effect
C) Resonance
D) Hyperconjugation
4. The +M effect of -OH group in phenol activates the ortho and para positions due to:
A) Withdrawal of electron density from the ring.
B) Donation of electron density into the ring via resonance.
C) Polarization of sigma bonds.
D) Temporary shift of pi electrons.
5. The inductive effect is considered a/an ______ effect.
A) Temporary
B) Permanent
C) Reversible
D) Instantaneous
6. Which of the following is a correct resonance contributor for the carboxylate ion (-COO-)?
A) A structure with one double bond and one single bond, with charges localized.
B) A structure with two single bonds and localized charges.
C) A structure where the negative charge and double bond are delocalized between the two oxygen atoms.
D) A structure with only single bonds.
7. The order of basicity of amines (e.g., NH3, RNH2, R2NH, R3N) is influenced by:
A) Inductive effect and solvation
B) Resonance only
C) Electromeric effect only
D) Hyperconjugation only
8. Which effect stabilizes alkyl radicals?
A) Inductive effect
B) Electromeric effect
C) Resonance
D) Hyperconjugation
9. The delocalization of electrons in resonance leads to:
A) Bond weakening
B) Charge dispersal
C) Localized charges
D) Decreased stability
10. In which of the following is the electromeric effect most likely to occur?
A) CH3-CH3
B) CH3-CH=CH-CH3
C) CH3-C≡C-CH3
D) CH3-CH2-CH3
11. The -I effect of a group generally leads to:
A) Increased electron density at the point of attachment.
B) Decreased electron density at the point of attachment.
C) No change in electron density.
D) Alternating electron density.
12. Which of the following is NOT a type of electronic effect?
A) Inductive effect
B) Mesomeric effect
C) Steric effect
D) Electromeric effect
13. Consider the acidity of phenol and ethanol. Phenol is more acidic due to:
A) Inductive effect of the phenyl group.
B) Resonance stabilization of the phenoxide ion.
C) Electromeric effect in the hydroxyl group.
D) Hyperconjugation in the phenyl ring.
14. The greater the number of alpha-hydrogens, the greater is the:
A) Inductive effect
B) Electromeric effect
C) Resonance stabilization
D) Hyperconjugation stabilization
15. Which of the following is a characteristic of resonance energy?
A) It is the energy of a single resonance structure.
B) It is the difference in energy between the most stable resonance structure and the hybrid.
C) It is the difference in energy between the actual molecule and the most stable hypothetical resonance structure.
D) It is the energy required to break all bonds.
16. The electromeric effect is a phenomenon of:
A) Electron displacement in sigma bonds
B) Permanent polarization of sigma bonds
C) Temporary displacement of pi electrons
D) Delocalization of electrons in rings
17. The +I effect of alkyl groups follows the order:
A) CH3- < CH3CH2- < (CH3)2CH- < (CH3)3C-
B) (CH3)3C- < (CH3)2CH- < CH3CH2- < CH3-
C) CH3- = CH3CH2- = (CH3)2CH- = (CH3)3C-
D) No specific order
18. Which effect is responsible for the stability of the tert-butyl carbocation?
A) Inductive effect
B) Electromeric effect
C) Resonance
D) Hyperconjugation
19. Hyperconjugation is most significant in:
A) Alkanes with no branching
B) Carbocations and alkenes with alpha-hydrogens
C) Aromatic compounds only
D) Molecules with polar bonds
20. Resonance structures are:
A) Actual structures of the molecule
B) Interconvertible forms of the molecule
C) Hypothetical structures contributing to the overall stability
D) Isomers of the molecule
21. The presence of a double bond in a molecule allows for:
A) Inductive effect only
B) Electromeric effect and resonance
C) Hyperconjugation only
D) Permanent sigma bond polarization
22. Which of the following shows the correct order of -I strength?
A) I > Br > Cl > F
B) F > Cl > Br > I
C) Cl > F > Br > I
D) Br > I > Cl > F
23. The inductive effect is transmitted through:
A) Pi bonds
B) Sigma bonds
C) Lone pairs
D) Aromatic systems
24. In electrophilic aromatic substitution, the activating groups are those that:
A) Deactivate the ring by withdrawing electron density.
B) Activate the ring by donating electron density.
C) Direct substitution to the meta position.
D) Stabilize the intermediate carbocation.
25. Which of the following groups shows a -M effect?
A) -OH
B) -NH2
C) -OR
D) -NO2
26. The +M effect is associated with:
A) Electron withdrawing groups
B) Electron donating groups
C) Groups with lone pairs or pi electrons that can be donated
D) Groups with empty orbitals
27. Which effect is responsible for the increased stability of the allyl carbocation?
A) Inductive effect
B) Electromeric effect
C) Resonance
D) Hyperconjugation
28. Consider the acidity of formic acid, acetic acid, and propanoic acid. The acidity decreases in the order:
A) Propanoic acid > Acetic acid > Formic acid
B) Formic acid > Acetic acid > Propanoic acid
C) Acetic acid > Formic acid > Propanoic acid
D) Formic acid > Propanoic acid > Acetic acid
29. The stability order of carbanions is generally the reverse of carbocations due to:
A) Inductive effect
B) Resonance effect
C) Electromeric effect
D) Hyperconjugation
30. Which of the following is a correct resonance structure of benzene?
A) A structure with alternating single and double bonds in fixed positions.
B) A structure showing localized pi electrons.
C) A structure with delocalized pi electrons represented by a circle.
D) A structure with only single bonds.
31. The electromeric effect is observed in molecules containing:
A) Only sigma bonds
B) Only single bonds
C) Multiple bonds (double or triple bonds)
D) Aromatic rings
32. Which of the following has the strongest -I effect?
A) -F
B) -Cl
C) -Br
D) -I
33. The +I effect of an alkyl group is generally:
A) Strong
B) Weak
C) Negligible
D) Variable
34. The stability of alkenes increases with:
A) Decreasing number of alpha-hydrogens
B) Increasing number of alpha-hydrogens
C) Decreasing number of pi bonds
D) Increasing number of sigma bonds
35. Which of the following is the most stable carbocation based on hyperconjugation?
A) Methyl carbocation (CH3+)
B) Primary carbocation (RCH2+)
C) Secondary carbocation (R2CH+)
D) Tertiary carbocation (R3C+)
36. Hyperconjugation involves the overlap of:
A) Pi (π) orbitals with empty p-orbitals
B) Sigma (σ) orbitals of C-H or C-C bonds with adjacent empty p-orbitals or π-orbitals
C) Lone pair orbitals with pi orbitals
D) Only pi-pi overlap
37. Hyperconjugation is also known as:
A) Electromeric effect
B) Sigma-pi conjugation
C) Inductive resonance
D) No-bond resonance
38. Resonance leads to:
A) Decreased stability
B) Increased stability
C) No change in stability
D) Alternating stability
39. In resonance, the actual structure of the molecule is a:
A) Average of all contributing structures
B) Sum of all contributing structures
C) One of the contributing structures
D) None of the above
40. Which of the following molecules exhibits resonance?
A) Methane (CH4)
B) Ethane (C2H6)
C) Benzene (C6H6)
D) Water (H2O)
41. The resonance effect is associated with the delocalization of:
A) Sigma (σ) electrons
B) Pi (π) electrons and lone pairs
C) Only sigma electrons
D) Only lone pair electrons
42. Which symbol is used to represent the electromeric effect?
A) ↔
B) →
C) ⇌
D) ⟷
43. In the electromeric effect, the displacement of pi electrons occurs towards:
A) The more electronegative atom
B) The less electronegative atom
C) The atom from which the reagent attacks
D) Away from the functional group
44. The electromeric effect involves the displacement of:
A) Sigma (σ) electrons
B) Pi (π) electrons
C) Lone pair electrons
D) All electrons
45. Which of the following is a temporary effect, occurring only in the presence of an attacking reagent?
A) Inductive effect
B) Resonance effect
C) Electromeric effect
D) Hyperconjugation
46. The strength of the inductive effect decreases with:
A) Increase in electronegativity difference
B) Decrease in electronegativity difference
C) Increase in distance from the functional group
D) Decrease in distance from the functional group
47. Which group will exhibit a negative inductive effect (-I)?
A) -CH3
B) -NH2
C) -OH
D) -Br
48. Which group will exhibit a positive inductive effect (+I)?
A) -NO2
B) -CN
C) -CH3
D) -Cl
49. The inductive effect involves the displacement of which type of electrons?
A) Pi (π) electrons
B) Lone pair electrons
C) Sigma (σ) electrons
D) All of the above
50. Which of the following is a permanent effect in organic chemistry?
A) Electromeric effect
B) Inductive effect
C) Resonance effect
D) Hyperconjugation effect
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