JEE Main Organic Chemistry: Bond Fission, Electrophiles & Nucleophiles

Q 1 :

The difference in energy between the actual structure and the lowest energy resonance structure for the given compound is [2024]

electromeric energy
ionization energy
hyperconjugation energy
resonance energy

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(4)

Resonance energy is defined as the difference in energy between the actual structure (real hybrid) and the lowest energy resonance structure for the given compound.

Q 2 :

Which among the following is incorrect statement? [2024]

Electromeric effect dominates over inductive effect.
The electromeric effect is, temporary effect.
The organic compound shows electromeric effect in the presence of the reagent only.
Hydrogen ion ( $H^{+}$ ) shows negative electromeric effect.

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(4)

Electromeric effect (E) is a temporary effect that involves the complete transfer of a shared pair of electrons to one or the other atom joined by a multiple bond (double or triple).

It occurs only in the presence of an attacking reagent and direction of $π$ electron shift always facilitates the reaction.

Electromeric effect is said to be +E when the displacement of $π$ electrons is towards the attacking reagent and -E when the displacement of $π$ electrons is away from the attacking reagent. $H^{+}$ shows positive electromeric effect.

Q 3 :

The interaction between $π$ bond and lone pair of electrons present on an adjacent atom is responsible for [2024]

Resonance effect
Electromeric effect
Inductive effect
Hyperconjugation

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(1)

Q 4 :

Ionic reactions with organic compounds proceed through: [2024]
(A) homolytic bond cleavage
(B) heterolytic bond cleavage
(C) free radical formation
(D) primary free radical
(E) secondary free radical
Choose the correct answer from the options given below:

(A) only
(C) only
(B) only
(D) and (E) only

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(3)

Ions in organic reaction are generated by heterolytic cleavage of bond. So ionic reactions with organic compounds proceed through heterolytic bond cleavage.

Homolytic bond cleavage results in formation of free radicals.

Q 5 :

The functional group that shows negative resonance effect is: [2024]

—OH
—OR
—COOH
— ${NH}_{2}$

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(3)

Groups of the type $- X = Y$ and $- X \equiv Y$ act as –M groups. –COOH is –M group.

Groups which have lone pair containing first atom act as +M groups. –OH, –OR and $- {NH}_{2}$ are +M groups.

Q 6 :

Match List-I with List-II: [2024]

Choose the correct answer from the options given below

(A) – (II), (B) – (IV), (C) – (III), (D) – (I)
(A) – (IV), (B) – (III), (C) – (I), (D) – (II)
(A) – (III), (B) – (I), (C) – (II), (D) – (IV)
(A) – (I), (B) – (II), (C) – (IV), (D) – (III)

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(2)

A group is said to be +M group, when it supplies $π$ electrons to the system through resonance. A group is said to be –M group, when it supplies $π$ electrons to the system through resonance. Electromeric effect is said to be +E when the displacement of $π$ electrons is towards the attacking reagent and –E when the displacement of $π$ electrons is away from the attacking reagent.

Q 7 :

The correct stability order of the following resonance structures of [2024]

II > I > III
III > II > I
II > III > I
I > II > III

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(2)

Neutral resonating structures are more stable than charged resonating structure. Amongst charged resonating structures, those structures which have negative charge on more electronegative atom and positive charge on less electronegative atom are more stable.

Q 8 :

Relative stability of the contributing structures is: [2024]

(I) > (III) > (II)
(III) > (II) > (I)
(I) > (II) > (III)
(II) > (I) > (III)

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(3)

Neutral resonating structures are more stable than charged resonating structures. Amongst charged resonating structures, those carrying negative charge on more electronegative atom and positive charge on less electronegative atom are more stable.

Q 9 :

For the compounds: [2024]

The increasing order of boiling point is:
Choose the correct answer from the option given below:

(B) < (A) < (C) < (D)
(B) < (A) < (D) < (C)
(D) < (C) < (A) < (B)
(A) < (B) < (C) < (D)

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(1)

Q 10 :

The order of relative stability of the contributing structure is: [2024]

Choose the correct answer from the options given below:

I > II > III
II > I > III
I = II = III
III > II > I

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(1)

Q 11 :

How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects? [2024]

(4)

Q 12 :

Given below are two statements : [2025]

Statement I : Hyperconjugation is not a permanent effect.

Statement II : In general, greater the number of alkyl groups attached to a positively charged C-atom, greater is the hyperconjugation interaction and stabilization of the cation.

In the light of the above statements, choose the correct answer from the options given below:

Statement I is true but Statement II is false.
Both Statement I and Statement II are false.
Statement I is false but Statement II is true.
Both Statement I and Statement II are true.

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(3)

Hyperconjugation is a permanent effect.

Q 13 :

Given below are two statements. [2025]

Statement I : The dipole moment of $\overset{4}{C} H_{3} - \overset{3}{C} H = \overset{2}{C} H - \overset{1}{C} H = O$ is greater than $\overset{4}{C} H_{3} - \overset{3}{C} H_{2} - \overset{2}{C} H_{2} - \overset{1}{C} H = O$

Statement II : $C_{1} - C_{2}$ bond length of $\underset{4}{{CH}_{3}} - \underset{3}{CH} = \underset{2}{CH} - \underset{1}{CH} = O$ is greater than $C_{1} - C_{2}$ bond length of $\underset{4}{{CH}_{3}} - \underset{3}{{CH}_{2}} - \underset{2}{{CH}_{2}} - \underset{1}{CH} = O$

In the light of the above statements, choose the correct answer from the options given below:

Statement I is false but Statement II is true.
Both Statement I and Statement II are false.
Statement I is true but Statement II is false.
Both Statement I and Statement II are true.

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(3)

$δ_{1} > δ_{2} as electron withdrawal by - M effect is more. Also d_{1} > d_{2}, thus μ_{1} > μ_{2} . Due to partial double bond character x < y .$

Q 14 :

Total number of nucleophiles from the following is : [2025]

6
4
5
7

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3

4

(3)

${NH}_{3}, PhSH, {({CH}_{3})}_{2} S, {CH}_{2} = {CH}_{2}$ and ${OH}^{-}$ are nucleophiles. ${({CH}_{3})}_{2} C = O$ is generally considered as electrophilic. The carbonyl carbon carries partial positive charge and is susceptible to attack by nucleophiles. Same is the case with ${({CH}_{3})}_{2} C = {NCH}_{3}$ .

Q 15 :

What is the correct order of acidity of the protons marked A–D in the given compounds? [2023]

$H_{C} > H_{D} > H_{A} > H_{B}$
$H_{C} > H_{D} > H_{B} > H_{A}$
$H_{C} > H_{A} > H_{D} > H_{B}$
$H_{D} > H_{C} > H_{B} > H_{A}$

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(1)

$(- COOH)$ carboxylic acid is more acidic than alcohol or terminal alkyne. $K_{a} = H_{C} > H_{D} > H_{A} > H_{B}$

Q 16 :

The number of hyperconjugation structures involved to stabilize carbocation formed in the above reaction is ________. [2023]

(7)

Q 17 :

Arrange the following alkenes in decreasing order of stability. [2026]

Choose the correct answer from the options given below:

III > II > I > IV
I > III > IV > II
I > III > II > IV
III > I > II > IV

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(3)

Q 18 :

The cyclic cations having the same number of hyperconjugation are:

(A) (B)

(C) (D)

Choose the correct answer from the options given below: [2026]

A and B Only
B and C Only
A, C and D Only
A and C Only

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(4)

Ans. – (4) A & C

Q 19 :

Given below are two statements:

Statement I: ${({CH}_{3})}_{3} \overset{\oplus}{C}$ is more stable than $\overset{\oplus}{{CH}_{3}}$ as nine hyperconjugation interactions are possible in ${({CH}_{3})}_{3} \overset{\oplus}{C}$

Statement II: $\overset{\oplus}{{CH}_{3}}$ is less stable than ${({CH}_{3})}_{3} \overset{\oplus}{C}$ as only three hyperconjugation interactions are possible in $\overset{\oplus}{{CH}_{3}}$

In the light of the above statements, choose the correct answer from the options given below: [2026]

Both Statement I and Statement II are true
Both Statement I and Statement II are false
Statement I is false but Statement II is true
Statement I is true but Statement II is false

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(4)

$S - 1 : {({CH}_{3})}_{3} C^{+} > \overset{+}{C} H_{3}; due to hyperconjugation interaction$

$S-2 : False$

Q 20 :

Among the following, the number of aromatic compound(s) is.....

(6)

CONCEPTUAL

Q 21 :

Number of ambidentate nucleophiles among the following

$C N^{-}, S C N^{-}, O H^{-}, C N O^{-}, S O_{4}^{2 -}, H C O_{2}^{-}, N O_{2}^{-}, N O_{3}^{-}$

(4)

$C N^{-}, S C N^{-}, N O_{2}^{-}, C N O^{-}$

Q 22 :

Number of electrophilic centre in the given compound is __________

(3)

Q 23 :

Number of H-atoms involved in hyper conjugation in the following is

(0)

Q 24 :

Consider the following molecules species:

The correct order of carbon-oxygen double bond length is: [2026]

$x > y > z$
$y > z > x$
$z > x > y$
$x > z > y$

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(4)

Bond length $\propto 1 / bond order$ . Thus bond length of $C - O$ bond follows the order : $x > z > y$

Q 25 :

Given below are two statements:

Statement I: On the basis of inductive effect, the order of stability of alkyl carbanions is ${CH}_{3}^{-} > {CH}_{3} {-CH}_{2}^{-} > {({CH}_{3})}_{2} {CH}^{-} > {({CH}_{3})}_{3} C^{-}$ .

Statement II: Alkyl and benzyl carbanions are more stabilised by inductive effect and not by resonance effect.

In the light of the above statements choose the correct answer from the options given below: [2026]

Both Statement I and Statement II are correct
Both Statement I and Statement II are incorrect
Statement I is correct but Statement II is incorrect
Statement I is incorrect but Statement II is correct

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(3)

Allyl and benzyl carbanions are stabilized by resonance.

Q 26 :

Shown below is the structure of methyl acetate with three different $α$ , $β$ and $γ$ carbon-oxygen bonds.

. The correct order of bond lengths of these bonds is: [2026]

$α > β > γ$
$α < β < γ$
$α = β = γ$
$α < β = γ$

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(2)

$Bond length \propto \frac{1}{Bond order}$

Q 27 :

Increasing order of electron withdrawing power of following functional groups is: [2026]

a) $- CN$

b) $- COOH$

c) $- {NO}_{2}$

d) $- I$

c < b < d < a
c < a < b < d
d < b < a < c
a < b < c < d

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(3)

$- I$ groups:

Q 28 :

For the given molecule, " $x$ ", the preferred site for the attack of the electrophile is: [2026]

Predominantly at " $r$ "
" $r$ " and " $u$ "
" $p$ " and " $s$ "
Predominantly at " $u$ "

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(4)

At $' u'$ electron density is more and steric hindrance is less. Hence it is the preferred site to attack for an electrophile.

Topic Question Set

Q 1 :

The difference in energy between the actual structure and the lowest energy resonance structure for the given compound is [2024]

Q 2 :

Which among the following is incorrect statement? [2024]

Q 3 :

The interaction between $π$ bond and lone pair of electrons present on an adjacent atom is responsible for [2024]

Q 4 :

Ionic reactions with organic compounds proceed through: [2024]
(A) homolytic bond cleavage
(B) heterolytic bond cleavage
(C) free radical formation
(D) primary free radical
(E) secondary free radical
Choose the correct answer from the options given below:

Q 5 :

The functional group that shows negative resonance effect is: [2024]

Q 6 :

Match List-I with List-II: [2024]

Choose the correct answer from the options given below

Q 7 :

The correct stability order of the following resonance structures of [2024]

Q 8 :

Relative stability of the contributing structures is: [2024]

Q 9 :

For the compounds: [2024]

The increasing order of boiling point is:
Choose the correct answer from the option given below:

Q 10 :

The order of relative stability of the contributing structure is: [2024]

Choose the correct answer from the options given below:

Q 11 :

How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects? [2024]

Q 14 :

Total number of nucleophiles from the following is : [2025]

Q 15 :

What is the correct order of acidity of the protons marked A–D in the given compounds? [2023]

Q 16 :

The number of hyperconjugation structures involved to stabilize carbocation formed in the above reaction is ________. [2023]

Q 17 :

Arrange the following alkenes in decreasing order of stability. [2026]

Choose the correct answer from the options given below:

Q 18 :

The cyclic cations having the same number of hyperconjugation are:

(A) (B)

(C) (D)

Choose the correct answer from the options given below: [2026]

Q 20 :

Among the following, the number of aromatic compound(s) is.....

Q 21 :

Number of ambidentate nucleophiles among the following

$C N^{-}, S C N^{-}, O H^{-}, C N O^{-}, S O_{4}^{2 -}, H C O_{2}^{-}, N O_{2}^{-}, N O_{3}^{-}$

Q 22 :

Number of electrophilic centre in the given compound is __________

Q 23 :

Number of H-atoms involved in hyper conjugation in the following is

Q 24 :

Consider the following molecules species:

The correct order of carbon-oxygen double bond length is: [2026]

Q 26 :

Shown below is the structure of methyl acetate with three different $α$ , $β$ and $γ$ carbon-oxygen bonds.

. The correct order of bond lengths of these bonds is: [2026]

Q 27 :

Increasing order of electron withdrawing power of following functional groups is: [2026]

a) $- CN$

b) $- COOH$

c) $- {NO}_{2}$

d) $- I$

Q 28 :

For the given molecule, " $x$ ", the preferred site for the attack of the electrophile is: [2026]

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Topic Question Set

Q 1 : The difference in energy between the actual structure and the lowest energy resonance structure for the given compound is [2024]

Q 2 : Which among the following is incorrect statement? [2024]

Q 3 : The interaction between π bond and lone pair of electrons present on an adjacent atom is responsible for [2024]

Q 4 : Ionic reactions with organic compounds proceed through: [2024] (A) homolytic bond cleavage (B) heterolytic bond cleavage (C) free radical formation (D) primary free radical (E) secondary free radical Choose the correct answer from the options given below:

Q 5 : The functional group that shows negative resonance effect is: [2024]

Q 6 : Match List-I with List-II: [2024] Choose the correct answer from the options given below

Q 7 : The correct stability order of the following resonance structures of [2024]

Q 8 : Relative stability of the contributing structures is: [2024]

Q 9 : For the compounds: [2024] The increasing order of boiling point is: Choose the correct answer from the option given below:

Q 10 : The order of relative stability of the contributing structure is: [2024] Choose the correct answer from the options given below:

Q 11 : How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects? [2024]

Q 14 : Total number of nucleophiles from the following is : [2025]

Q 15 : What is the correct order of acidity of the protons marked A–D in the given compounds? [2023]

Q 16 : The number of hyperconjugation structures involved to stabilize carbocation formed in the above reaction is ________. [2023]

Q 17 : Arrange the following alkenes in decreasing order of stability. [2026] Choose the correct answer from the options given below:

Q 18 : The cyclic cations having the same number of hyperconjugation are: (A) (B) (C) (D) Choose the correct answer from the options given below: [2026]

Q 20 : Among the following, the number of aromatic compound(s) is.....

Q 21 : Number of ambidentate nucleophiles among the following CN-, SCN-, OH-, CNO-, SO42-, HCO2-, NO2-, NO3-

Q 22 : Number of electrophilic centre in the given compound is __________

Q 23 : Number of H-atoms involved in hyper conjugation in the following is

Q 24 : Consider the following molecules species: The correct order of carbon-oxygen double bond length is: [2026]

Q 26 : Shown below is the structure of methyl acetate with three different α, β and γ carbon-oxygen bonds. . The correct order of bond lengths of these bonds is: [2026]

Q 27 : Increasing order of electron withdrawing power of following functional groups is: [2026] a) -CN b) -COOH c) -NO2 d) -I

Q 28 : For the given molecule, "x", the preferred site for the attack of the electrophile is: [2026]

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Q 1 :

The difference in energy between the actual structure and the lowest energy resonance structure for the given compound is [2024]

Q 2 :

Which among the following is incorrect statement? [2024]

Q 3 :

The interaction between $π$ bond and lone pair of electrons present on an adjacent atom is responsible for [2024]

Q 4 :

Ionic reactions with organic compounds proceed through: [2024]
(A) homolytic bond cleavage
(B) heterolytic bond cleavage
(C) free radical formation
(D) primary free radical
(E) secondary free radical
Choose the correct answer from the options given below:

Q 5 :

The functional group that shows negative resonance effect is: [2024]

Q 6 :

Match List-I with List-II: [2024]

Choose the correct answer from the options given below

Q 7 :

The correct stability order of the following resonance structures of [2024]

Q 8 :

Relative stability of the contributing structures is: [2024]

Q 9 :

For the compounds: [2024]

The increasing order of boiling point is:
Choose the correct answer from the option given below:

Q 10 :

The order of relative stability of the contributing structure is: [2024]

Choose the correct answer from the options given below:

Q 11 :

How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects? [2024]

Q 14 :

Total number of nucleophiles from the following is : [2025]

Q 15 :

What is the correct order of acidity of the protons marked A–D in the given compounds? [2023]

Q 16 :

The number of hyperconjugation structures involved to stabilize carbocation formed in the above reaction is ________. [2023]

Q 17 :

Arrange the following alkenes in decreasing order of stability. [2026]

Choose the correct answer from the options given below:

Q 18 :

The cyclic cations having the same number of hyperconjugation are:

(A) (B)

(C) (D)

Choose the correct answer from the options given below: [2026]

Q 20 :

Among the following, the number of aromatic compound(s) is.....

Q 21 :

Number of ambidentate nucleophiles among the following

$C N^{-}, S C N^{-}, O H^{-}, C N O^{-}, S O_{4}^{2 -}, H C O_{2}^{-}, N O_{2}^{-}, N O_{3}^{-}$

Q 22 :

Number of electrophilic centre in the given compound is __________

Q 23 :

Number of H-atoms involved in hyper conjugation in the following is

Q 24 :

Consider the following molecules species:

The correct order of carbon-oxygen double bond length is: [2026]

Q 26 :

Shown below is the structure of methyl acetate with three different $α$ , $β$ and $γ$ carbon-oxygen bonds.

. The correct order of bond lengths of these bonds is: [2026]

Q 27 :

Increasing order of electron withdrawing power of following functional groups is: [2026]

a) $- CN$

b) $- COOH$

c) $- {NO}_{2}$

d) $- I$

Q 28 :

For the given molecule, " $x$ ", the preferred site for the attack of the electrophile is: [2026]