Inductive effect in organic molecules is transmitted through
A π-bonds
B σ-bonds
C hydrogen bonds
D metallic bonds
Inductive effect is the permanent displacement of σ-electrons due to electronegativity differences.
The inductive effect decreases rapidly with increase in
A temperature
B molecular mass
C distance along carbon chain
D resonance energy
Inductive effect is distance dependent and weakens with increasing bond distance.
Which group shows the strongest −I effect
A –CH₃
B –OH
C –NO₂
D –C₂H₅
The nitro group strongly withdraws electrons due to high electronegativity and multiple bonds.
Which of the following groups shows +I effect
A –NO₂
B –CN
C –CH₃
D –COOH
Alkyl groups donate electrons through σ-bonds, showing +I effect.
Increasing +I effect generally increases
A acidity
B basicity
C electrophilicity
D electronegativity
Electron donation increases electron density on basic centers, enhancing basic strength.
Resonance effect involves the delocalization of
A σ-electrons
B nuclei
C π-electrons or lone pairs
D protons
Resonance involves delocalization of π-electrons or lone pair electrons over conjugated systems.
Resonance structures differ from each other in the position of
A atoms
B σ-bonds
C electrons
D nuclei
Only electron positions change; nuclei and σ-framework remain the same.
The actual structure of a molecule showing resonance is
A one of the canonical forms
B a rapidly oscillating structure
C a resonance hybrid
D the least stable form
The real molecule is a hybrid of all canonical forms and is more stable than any single form.
Which group shows a −R (−M) effect
A –NH₂
B –OH
C –NO₂
D –OCH₃
Nitro group withdraws electrons by resonance due to its electron-deficient nature.
Which group shows a +R (+M) effect
A –NO₂
B –CN
C –NH₂
D –COOH
Amino group donates lone pair electrons into the conjugated system.
Hyperconjugation involves interaction between
A π–π orbitals
B σ(C–H) and adjacent π-system
C σ–σ orbitals
D lone pair–lone pair
Hyperconjugation is due to overlap of C–H σ-bonds with adjacent π-orbitals.
Hyperconjugation is also known as
A mesomeric effect
B no-bond resonance
C electromeric effect
D field effect
It is represented by structures where a C–H bond appears broken.
Hyperconjugation stabilizes
A carbocations
B carbanions
C free radicals
D both A and C
Electron donation from σ-bonds stabilizes electron-deficient carbocations and radicals.
Number of hyperconjugative structures depends on number of
A carbon atoms
B π-bonds
C adjacent C–H bonds
D lone pairs
More α-hydrogens lead to more hyperconjugative structures.
Hyperconjugation is absent in
A ethyl carbocation
B methyl carbocation
C isopropyl carbocation
D tert-butyl carbocation
Methyl carbocation has no α-hydrogen for hyperconjugation.
Order of carbocation stability due to hyperconjugation is
A 1° > 2° > 3°
B 2° > 1° > 3°
C 3° > 2° > 1°
D 1° > 3° > 2°
More alkyl groups give more hyperconjugation and +I effect.
Which alkene is most stable
A ethene
B propene
C but-1-ene
D 2-methyl-2-butene
Greater substitution gives greater hyperconjugative stabilization.
−I effect increases
A basicity
B acidity
C nucleophilicity
D electron density
Electron-withdrawing groups stabilize conjugate base, increasing acidity.
Resonance effect is stronger than inductive effect because
A it acts through σ-bonds
B it is temporary
C it involves delocalization of electrons
D it acts only over short distance
Delocalization provides significant stabilization energy.
Correct order of −I effect among halogens is
A F > Cl > Br > I
B I > Br > Cl > F
C Cl > F > Br > I
D Br > Cl > F > I
Inductive effect follows electronegativity order.
Hyperconjugation requires the presence of
A lone pair
B π-bond
C α-hydrogen
D triple bond
σ(C–H) bond adjacent to unsaturation is essential.
Which effect explains o,p-directing nature of –OH group
A −I effect
B +R effect
C hyperconjugation
D steric effect
Lone pair donation activates ortho and para positions.
Stability of resonance hybrid is
A equal to most stable structure
B less than any structure
C greater than any individual structure
D equal to average of structures
Resonance energy stabilizes the molecule.
Which group decreases electron density on benzene ring
A –NH₂
B –OCH₃
C –CH₃
D –NO₂
Strong −I and −R effects withdraw electrons.
Hyperconjugation explains
A acidity of phenol
B stability of alkenes
C aromaticity of benzene
D inductive effect
More substituted alkenes are more stable due to hyperconjugation.
Which effect operates only in conjugated systems
A inductive
B hyperconjugation
C resonance
D steric
Resonance requires overlap of p-orbitals in conjugation.
Alkyl groups are
A electron withdrawing
B electron donating
C neutral
D −R groups
Alkyl groups show +I effect.
Which statement is correct
A Inductive effect is temporary
B Resonance effect is permanent
C Hyperconjugation requires lone pair
D Inductive acts through π-bonds
Resonance exists as long as conjugation exists.
Most stable carbocation is
A CH₃⁺
B C₂H₅⁺
C (CH₃)₂CH⁺
D (CH₃)₃C⁺
Maximum hyperconjugation and +I effect.
Inductive effect is strongest through
A double bond
B triple bond
C single bond
D hydrogen bond
Inductive effect is transmitted via σ-bonds.
Which effect explains decreasing basicity of amines in water
A inductive
B resonance
C solvation
D hyperconjugation
Solvation stabilizes smaller amines more effectively.
Resonance energy represents
A bond energy
B stabilization due to resonance
C kinetic energy
D entropy change
It is the extra stability of resonance hybrid.
Hyperconjugation increases stability by
A increasing bond length
B electron donation
C proton transfer
D sigma bond cleavage
Donation from σ-bonds stabilizes electron-deficient centers.
Which compound shows maximum hyperconjugation
A CH₂=CH₂
B CH₃–CH=CH₂
C (CH₃)₂C=CH₂
D (CH₃)₂C=C(CH₃)₂
Maximum number of α-hydrogens.
Inductive effect operates in
A saturated compounds only
B unsaturated compounds only
C both saturated and unsaturated
D aromatic compounds only
It depends on σ-bonds, present in all.
Resonance structures must have same
A number of atoms
B energy
C stability
D charge distribution
Only electron distribution changes.
Which group has strongest +R effect
A –CH₃
B –NH₂
C –Cl
D –COOH
Lone pair donation is strongest in –NH₂.
Hyperconjugation is not observed in
A alkenes
B carbocations
C carbanions
D free radicals
Carbanions are electron-rich and not stabilized by hyperconjugation.
Which effect explains stability of benzyl carbocation
A inductive
B resonance
C hyperconjugation
D steric
Positive charge is delocalized over benzene ring.
−R groups in benzene are generally
A o,p-directing
B meta-directing
C activating
D electron donating
−R groups withdraw electrons and deactivate o,p positions.
Hyperconjugation increases with
A fewer α-hydrogens
B more α-hydrogens
C more electronegative atoms
D higher acidity
More σ(C–H) bonds available for donation.
Which effect is permanent
A inductive
B electromeric
C resonance
D both A and C
Inductive and resonance effects are permanent.
The most electron withdrawing group is
A –CH₃
B –NH₂
C –NO₂
D –OCH₃
Strong −I and −R effects.
Hyperconjugation is maximum in
A ethene
B propene
C isobutene
D tetramethylethene
Maximum α-hydrogens.
Inductive effect depends on
A electronegativity difference
B molecular geometry
C temperature
D pressure
Greater difference causes stronger polarization.
Resonance cannot occur in
A benzene
B nitrobenzene
C ethane
D aniline
No conjugated π-system.
Which statement is incorrect
A Hyperconjugation stabilizes carbocations
B Resonance stabilizes benzene
C Inductive effect acts through π-bonds
D Alkyl groups show +I effect
Inductive effect acts through σ-bonds, not π-bonds.
The +I effect of alkyl groups increases in the order
A CH₃ < C₂H₅ < (CH₃)₂CH < (CH₃)₃C
B (CH₃)₃C < (CH₃)₂CH < C₂H₅ < CH₃
C CH₃ = C₂H₅ = (CH₃)₂CH
D random order
More alkyl substitution → stronger +I effect.
Which effect explains planarity of benzene
A inductive
B resonance
C hyperconjugation
D steric
Delocalization requires planar structure.
Correct statement is
A Hyperconjugation and resonance are same
B Inductive effect is distance dependent
C Resonance effect is distance dependent
D Hyperconjugation acts through lone pairs only
Inductive effect decreases with distance; resonance does not.