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 \({\mathrm{-\mathrm{CH}_{3}}}\) 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) \(\mathrm{p}\)-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:
Acidic because of resonance stabilisation of phenoxide ion. \({\rm{ - C}}{{\rm{H}}_{\rm{3}}}\) group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic). \(-\mathrm{NO}_{2}\) withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased. (IV) Lower acidity in case of m-isomer as compared to \(\mathrm{p}\)-isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with \(-\mathrm{NO}_{2}\) group. Thus, m-nitorphenol < p-nitrophenol.
CHXII11:ALCOHOLS, PHENOLS AND ETHERS
323275
For the given compounds, the correct order of increasing \({\mathrm{\mathrm{pK}_{\mathrm{a}}}}\) value: Choose the correct answer from the options given below
Relative basic character of their conjugated bases which for \({{\text{H}}_2}{\text{O,}}{{\text{C}}_2}{{\text{H}}_2},{{\text{H}}_2}{\text{C}}{{\text{O}}_3}\) and \({{\text{C}}_6}{{\text{H}}_5}{\text{OH}}\) are \({\text{OH}},{\text{HC}} \equiv {{\text{C}}^ - },{\text{HCO}}_3^ - ,{{\text{C}}_6}{{\text{H}}_5}{{\text{O}}^ - }\) Thus the acidic character of the four corresponding acids will be \(\mathrm{H}_{2} \mathrm{CO}_{3}>\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{HC} \equiv \mathrm{CH}\).
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 \({\mathrm{-\mathrm{CH}_{3}}}\) 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) \(\mathrm{p}\)-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:
Acidic because of resonance stabilisation of phenoxide ion. \({\rm{ - C}}{{\rm{H}}_{\rm{3}}}\) group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic). \(-\mathrm{NO}_{2}\) withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased. (IV) Lower acidity in case of m-isomer as compared to \(\mathrm{p}\)-isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with \(-\mathrm{NO}_{2}\) group. Thus, m-nitorphenol < p-nitrophenol.
CHXII11:ALCOHOLS, PHENOLS AND ETHERS
323275
For the given compounds, the correct order of increasing \({\mathrm{\mathrm{pK}_{\mathrm{a}}}}\) value: Choose the correct answer from the options given below
Relative basic character of their conjugated bases which for \({{\text{H}}_2}{\text{O,}}{{\text{C}}_2}{{\text{H}}_2},{{\text{H}}_2}{\text{C}}{{\text{O}}_3}\) and \({{\text{C}}_6}{{\text{H}}_5}{\text{OH}}\) are \({\text{OH}},{\text{HC}} \equiv {{\text{C}}^ - },{\text{HCO}}_3^ - ,{{\text{C}}_6}{{\text{H}}_5}{{\text{O}}^ - }\) Thus the acidic character of the four corresponding acids will be \(\mathrm{H}_{2} \mathrm{CO}_{3}>\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{HC} \equiv \mathrm{CH}\).
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 \({\mathrm{-\mathrm{CH}_{3}}}\) 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) \(\mathrm{p}\)-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:
Acidic because of resonance stabilisation of phenoxide ion. \({\rm{ - C}}{{\rm{H}}_{\rm{3}}}\) group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic). \(-\mathrm{NO}_{2}\) withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased. (IV) Lower acidity in case of m-isomer as compared to \(\mathrm{p}\)-isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with \(-\mathrm{NO}_{2}\) group. Thus, m-nitorphenol < p-nitrophenol.
CHXII11:ALCOHOLS, PHENOLS AND ETHERS
323275
For the given compounds, the correct order of increasing \({\mathrm{\mathrm{pK}_{\mathrm{a}}}}\) value: Choose the correct answer from the options given below
Relative basic character of their conjugated bases which for \({{\text{H}}_2}{\text{O,}}{{\text{C}}_2}{{\text{H}}_2},{{\text{H}}_2}{\text{C}}{{\text{O}}_3}\) and \({{\text{C}}_6}{{\text{H}}_5}{\text{OH}}\) are \({\text{OH}},{\text{HC}} \equiv {{\text{C}}^ - },{\text{HCO}}_3^ - ,{{\text{C}}_6}{{\text{H}}_5}{{\text{O}}^ - }\) Thus the acidic character of the four corresponding acids will be \(\mathrm{H}_{2} \mathrm{CO}_{3}>\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{HC} \equiv \mathrm{CH}\).
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 \({\mathrm{-\mathrm{CH}_{3}}}\) 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) \(\mathrm{p}\)-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:
Acidic because of resonance stabilisation of phenoxide ion. \({\rm{ - C}}{{\rm{H}}_{\rm{3}}}\) group release electrons, destabilises the phenoxide ion thus acidic nature is decreased ,hence II < I (acidic). \(-\mathrm{NO}_{2}\) withdraws electrons, stabilizes the phenoxide ion, hence acidity is increased. (IV) Lower acidity in case of m-isomer as compared to \(\mathrm{p}\)-isomer is explained by the fact that m-nitrophenoxide is stabilised by inductive effect only and no resonance effect operates with \(-\mathrm{NO}_{2}\) group. Thus, m-nitorphenol < p-nitrophenol.
CHXII11:ALCOHOLS, PHENOLS AND ETHERS
323275
For the given compounds, the correct order of increasing \({\mathrm{\mathrm{pK}_{\mathrm{a}}}}\) value: Choose the correct answer from the options given below
Relative basic character of their conjugated bases which for \({{\text{H}}_2}{\text{O,}}{{\text{C}}_2}{{\text{H}}_2},{{\text{H}}_2}{\text{C}}{{\text{O}}_3}\) and \({{\text{C}}_6}{{\text{H}}_5}{\text{OH}}\) are \({\text{OH}},{\text{HC}} \equiv {{\text{C}}^ - },{\text{HCO}}_3^ - ,{{\text{C}}_6}{{\text{H}}_5}{{\text{O}}^ - }\) Thus the acidic character of the four corresponding acids will be \(\mathrm{H}_{2} \mathrm{CO}_{3}>\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{HC} \equiv \mathrm{CH}\).
