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General Organic Chemistry II: Acids and Bases
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Acidic strength of organic compounds and pKa comparisons
JEE Main level
Single correct option
Difficulty 2 of 3
g2020
Which of the following is the correct order of decreasing acidic strength in water?
A
p
-
CH
X
3
C
X
6
H
X
4
SO
X
3
H
>
C
X
6
H
X
5
COOH
>
C
X
2
H
X
5
OH
>
C
X
6
H
X
5
OH
B
p
-
CH
X
3
C
X
6
H
X
4
SO
X
3
H
>
C
X
6
H
X
5
OH
>
C
X
6
H
X
5
COOH
>
C
X
2
H
X
5
OH
C
p
-
CH
X
3
C
X
6
H
X
4
SO
X
3
H
>
C
X
6
H
X
5
COOH
>
C
X
6
H
X
5
OH
>
C
X
2
H
X
5
OH
D
C
X
6
H
X
5
COOH
>
p
-
CH
X
3
C
X
6
H
X
4
SO
X
3
H
>
C
X
6
H
X
5
OH
>
C
X
2
H
X
5
OH
Answer: C
Approximate pKa values: 4-methylbenzenesulfonic acid about -2.8, benzoic acid 4.20, phenol 10.0, ethanol 15.9. A lower pKa is a stronger acid, giving the order sulfonic acid > benzoic acid > phenol > ethanol.
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