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CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323273 How many of the following compounds are less acidic as compared to phenol?
m-Nitrophenol, benzyl alcohol, o-cresol,
o-chlorophenol, ethanol, picric acid, cyclohexanol

1 1

2 2

3 3

4 4

Explanation:

Phenols are more acidic in nature than alcohols. Also, in phenols the presence of electron releasing groups like $- {CH}_{3}$ in o-cresol decreases the acidic strength. Thus benzyl alcohol, o-cresol, ethanol and cyclohexanol are less acidic than phenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323274 The correct order of acid strength of the following compounds is
(I) Phenol
(II) $p$ -cresol
(III) m-nitrophenol
(IV) p-nitrophenol

1 I

>

II

>

IV

>

III

2 III

>

II

>

I

>

IV

3 II

>

IV

>

I

>

III

4 IV

>

III

>

I

>

II

Explanation:

supporting img
Acidic because of resonance stabilisation of phenoxide ion.

$- C H_{3}$ group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic).

$- {NO}_{2}$ withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased.
(IV) Lower acidity in case of m-isomer as compared to $p$ -isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with $- {NO}_{2}$ group.
Thus, m-nitorphenol < p-nitrophenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323275 For the given compounds, the correct order of increasing ${pK}_{a}$ value:
supporting img
Choose the correct answer from the options given below

1 (II)

<

(IV)

<

(III)

<

(I)

<

(V)

2 (V)

<

(IV)

<

(II)

<

(I)

<

(III)

3 (IV)

<

(V)

<

(III)

<

(II)

<

(I)

4 (V)

<

(IV)

<

(III)

<

(II)

<

(I)

Explanation:

acidic nature $\propto - M$ effect & $-$ I effect $\propto \frac{1}{+ M effect} & \frac{1}{+ I effect}$ $-$
M effect is more dominated at $o / p$ positions.
supporting img

Hence the order of pKa values is (II) $<$ (IV) $<$ (III) $<$ (I) $<$ (V).

JEE Main - 2024

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323276 Correct increasing order of acidity is as follows:

1

H_{2} O, C_{2} H_{2}, H_{2} {CO}_{3}

, Phenol

2

C_{2} H_{2}, H_{2} O, H_{2} {CO}_{3}

, Phenol

3 Phenol,

C_{2} H_{2}, H_{2} {CO}_{3}, H_{2} O

4

C_{2} H_{2}, H_{2} O

, Phenol,

H_{2} {CO}_{3}

Explanation:

Relative basic character of their conjugated bases which for $H_{2} O, C_{2} H_{2}, H_{2} C O_{3}$ and $C_{6} H_{5} OH$ are $OH, HC \equiv C^{-}, {HCO}_{3}^{-}, C_{6} H_{5} O^{-}$
supporting img
Thus the acidic character of the four corresponding acids will be
$H_{2} {CO}_{3} > C_{6} H_{5} OH > H_{2} O > HC \equiv CH$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323273 How many of the following compounds are less acidic as compared to phenol?
m-Nitrophenol, benzyl alcohol, o-cresol,
o-chlorophenol, ethanol, picric acid, cyclohexanol

1 1

2 2

3 3

4 4

Explanation:

Phenols are more acidic in nature than alcohols. Also, in phenols the presence of electron releasing groups like $- {CH}_{3}$ in o-cresol decreases the acidic strength. Thus benzyl alcohol, o-cresol, ethanol and cyclohexanol are less acidic than phenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323274 The correct order of acid strength of the following compounds is
(I) Phenol
(II) $p$ -cresol
(III) m-nitrophenol
(IV) p-nitrophenol

1 I

>

II

>

IV

>

III

2 III

>

II

>

I

>

IV

3 II

>

IV

>

I

>

III

4 IV

>

III

>

I

>

II

Explanation:

supporting img
Acidic because of resonance stabilisation of phenoxide ion.

$- C H_{3}$ group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic).

$- {NO}_{2}$ withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased.
(IV) Lower acidity in case of m-isomer as compared to $p$ -isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with $- {NO}_{2}$ group.
Thus, m-nitorphenol < p-nitrophenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323275 For the given compounds, the correct order of increasing ${pK}_{a}$ value:
supporting img
Choose the correct answer from the options given below

1 (II)

<

(IV)

<

(III)

<

(I)

<

(V)

2 (V)

<

(IV)

<

(II)

<

(I)

<

(III)

3 (IV)

<

(V)

<

(III)

<

(II)

<

(I)

4 (V)

<

(IV)

<

(III)

<

(II)

<

(I)

Explanation:

acidic nature $\propto - M$ effect & $-$ I effect $\propto \frac{1}{+ M effect} & \frac{1}{+ I effect}$ $-$
M effect is more dominated at $o / p$ positions.
supporting img

Hence the order of pKa values is (II) $<$ (IV) $<$ (III) $<$ (I) $<$ (V).

JEE Main - 2024

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323276 Correct increasing order of acidity is as follows:

1

H_{2} O, C_{2} H_{2}, H_{2} {CO}_{3}

, Phenol

2

C_{2} H_{2}, H_{2} O, H_{2} {CO}_{3}

, Phenol

3 Phenol,

C_{2} H_{2}, H_{2} {CO}_{3}, H_{2} O

4

C_{2} H_{2}, H_{2} O

, Phenol,

H_{2} {CO}_{3}

Explanation:

Relative basic character of their conjugated bases which for $H_{2} O, C_{2} H_{2}, H_{2} C O_{3}$ and $C_{6} H_{5} OH$ are $OH, HC \equiv C^{-}, {HCO}_{3}^{-}, C_{6} H_{5} O^{-}$
supporting img
Thus the acidic character of the four corresponding acids will be
$H_{2} {CO}_{3} > C_{6} H_{5} OH > H_{2} O > HC \equiv CH$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323273 How many of the following compounds are less acidic as compared to phenol?
m-Nitrophenol, benzyl alcohol, o-cresol,
o-chlorophenol, ethanol, picric acid, cyclohexanol

1 1

2 2

3 3

4 4

Explanation:

Phenols are more acidic in nature than alcohols. Also, in phenols the presence of electron releasing groups like $- {CH}_{3}$ in o-cresol decreases the acidic strength. Thus benzyl alcohol, o-cresol, ethanol and cyclohexanol are less acidic than phenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323274 The correct order of acid strength of the following compounds is
(I) Phenol
(II) $p$ -cresol
(III) m-nitrophenol
(IV) p-nitrophenol

1 I

>

II

>

IV

>

III

2 III

>

II

>

I

>

IV

3 II

>

IV

>

I

>

III

4 IV

>

III

>

I

>

II

Explanation:

supporting img
Acidic because of resonance stabilisation of phenoxide ion.

$- C H_{3}$ group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic).

$- {NO}_{2}$ withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased.
(IV) Lower acidity in case of m-isomer as compared to $p$ -isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with $- {NO}_{2}$ group.
Thus, m-nitorphenol < p-nitrophenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323275 For the given compounds, the correct order of increasing ${pK}_{a}$ value:
supporting img
Choose the correct answer from the options given below

1 (II)

<

(IV)

<

(III)

<

(I)

<

(V)

2 (V)

<

(IV)

<

(II)

<

(I)

<

(III)

3 (IV)

<

(V)

<

(III)

<

(II)

<

(I)

4 (V)

<

(IV)

<

(III)

<

(II)

<

(I)

Explanation:

acidic nature $\propto - M$ effect & $-$ I effect $\propto \frac{1}{+ M effect} & \frac{1}{+ I effect}$ $-$
M effect is more dominated at $o / p$ positions.
supporting img

Hence the order of pKa values is (II) $<$ (IV) $<$ (III) $<$ (I) $<$ (V).

JEE Main - 2024

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323276 Correct increasing order of acidity is as follows:

1

H_{2} O, C_{2} H_{2}, H_{2} {CO}_{3}

, Phenol

2

C_{2} H_{2}, H_{2} O, H_{2} {CO}_{3}

, Phenol

3 Phenol,

C_{2} H_{2}, H_{2} {CO}_{3}, H_{2} O

4

C_{2} H_{2}, H_{2} O

, Phenol,

H_{2} {CO}_{3}

Explanation:

Relative basic character of their conjugated bases which for $H_{2} O, C_{2} H_{2}, H_{2} C O_{3}$ and $C_{6} H_{5} OH$ are $OH, HC \equiv C^{-}, {HCO}_{3}^{-}, C_{6} H_{5} O^{-}$
supporting img
Thus the acidic character of the four corresponding acids will be
$H_{2} {CO}_{3} > C_{6} H_{5} OH > H_{2} O > HC \equiv CH$ .

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323273 How many of the following compounds are less acidic as compared to phenol?
m-Nitrophenol, benzyl alcohol, o-cresol,
o-chlorophenol, ethanol, picric acid, cyclohexanol

1 1

2 2

3 3

4 4

Explanation:

Phenols are more acidic in nature than alcohols. Also, in phenols the presence of electron releasing groups like $- {CH}_{3}$ in o-cresol decreases the acidic strength. Thus benzyl alcohol, o-cresol, ethanol and cyclohexanol are less acidic than phenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323274 The correct order of acid strength of the following compounds is
(I) Phenol
(II) $p$ -cresol
(III) m-nitrophenol
(IV) p-nitrophenol

1 I

>

II

>

IV

>

III

2 III

>

II

>

I

>

IV

3 II

>

IV

>

I

>

III

4 IV

>

III

>

I

>

II

Explanation:

supporting img
Acidic because of resonance stabilisation of phenoxide ion.

$- C H_{3}$ group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic).

$- {NO}_{2}$ withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased.
(IV) Lower acidity in case of m-isomer as compared to $p$ -isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with $- {NO}_{2}$ group.
Thus, m-nitorphenol < p-nitrophenol.

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323275 For the given compounds, the correct order of increasing ${pK}_{a}$ value:
supporting img
Choose the correct answer from the options given below

1 (II)

<

(IV)

<

(III)

<

(I)

<

(V)

2 (V)

<

(IV)

<

(II)

<

(I)

<

(III)

3 (IV)

<

(V)

<

(III)

<

(II)

<

(I)

4 (V)

<

(IV)

<

(III)

<

(II)

<

(I)

Explanation:

acidic nature $\propto - M$ effect & $-$ I effect $\propto \frac{1}{+ M effect} & \frac{1}{+ I effect}$ $-$
M effect is more dominated at $o / p$ positions.
supporting img

Hence the order of pKa values is (II) $<$ (IV) $<$ (III) $<$ (I) $<$ (V).

JEE Main - 2024

CHXII11:ALCOHOLS, PHENOLS AND ETHERS

323276 Correct increasing order of acidity is as follows:

1

H_{2} O, C_{2} H_{2}, H_{2} {CO}_{3}

, Phenol

2

C_{2} H_{2}, H_{2} O, H_{2} {CO}_{3}

, Phenol

3 Phenol,

C_{2} H_{2}, H_{2} {CO}_{3}, H_{2} O

4

C_{2} H_{2}, H_{2} O

, Phenol,

H_{2} {CO}_{3}

Explanation:

Relative basic character of their conjugated bases which for $H_{2} O, C_{2} H_{2}, H_{2} C O_{3}$ and $C_{6} H_{5} OH$ are $OH, HC \equiv C^{-}, {HCO}_{3}^{-}, C_{6} H_{5} O^{-}$
supporting img
Thus the acidic character of the four corresponding acids will be
$H_{2} {CO}_{3} > C_{6} H_{5} OH > H_{2} O > HC \equiv CH$ .