Question

Among the following, which is the strongest acid?
(A) $CH{F_2} - C{H_2} - C{H_2} - COOH$
(B) $C{H_3} - C{H_2} - C{F_2} - COOH$
(C) $C{H_2}F - CHF - C{H_2} - COOH$
(D) $C{H_3} - C{F_2} - C{H_2} - COOH$

Answer 1

Inductive effect is defined as the effect in which the permanent delocalization of sigma electrons can be influenced by the groups present in it. There are two types of inductive effects. They have negative and positive inductive effects. When there is a presence of negative inductive groups the acidic nature will be increased.

Complete answer:
Electron withdrawing groups are the groups or molecules consisting of electron-withdrawing or electron-attracting nature. Some of the examples of electron-withdrawing groups are halides like fluoride, chloride, bromide, and iodide.
Acidic compounds are compounds that can release a hydrogen ion easily. Carboxylic acids are acidic compounds due to the ability to release hydrogen ions or protons. Faster is the release of the proton, more will be the acidic nature.
When the electron-withdrawing or electronegative atoms like fluorine are present nearer to the $- COOH$ group in the carboxylic acids. Then that acid will be more acidic.
In the given compounds, the compound has the structure of $C{H_3} - C{H_2} - C{F_2} - COOH$ has two fluorine atoms nearer to the $- COOH$ group. Thus, it is more acidic than the remaining given compounds.
Thus, among the given compounds, $C{H_3} - C{H_2} - C{F_2} - COOH$ is the strongest acid.
Option b is the correct one.

Note:
When the fluorine atoms are nearer to the $- COOH$ group, then the fluorine atom attracts electrons from the carbon atom and that carbon atom attracts electrons, thereby the hydrogen atom in $- COOH$ group can be easily lost from the compound results in more acidic nature.