Read the passage carefully and answer the Questions.

Carboxylic acids are the earliest organic compounds isolated from nature. These are also known as organic acids but are weaker acids as compared to mineral acids. However, they are more acidic than alcohols and phenols because of greater resonance stabilization of the parent acid and its conjugate base. The acidic strength is determined by the Ka, which is called the acidity constant. The greater the value of Ka, the greater the tendency of the acid to ionize and hence the stronger the acid. The acidic strength of the saturated aliphatic carboxylic acid depends upon the inductive effect and its position with respect to - COOH groups. Electron-donating substituents tend to decrease whereas electron -withdrawing substituents tend to increase the acidic strength. The acidic strength of the aromatic carboxylic acid, on the other hand depends upon both the inductive effect and the resonance effect of the substituents.

Arrange the following acids in decreasing order of acidity

(A) $CH_3CH_2OH$
(B) $CH_3COOH$
(C) $BrCH_2COOH$
(D) $C_6H_5CH_2COOH$

Choose the correct answer from the options given below:

(C), (D), (B), (A)

The correct answer is Option (2) → (C), (D), (B), (A) ##

Compound (C) $BrCH_2COOH$ (Bromoacetic acid): This is the strongest acid in the list. The presence of Bromine, an electron-withdrawing group ($-I$ effect), stabilizes the conjugate base by pulling electron density away from the carboxylate group.

Compound (D) $C_6H_5CH_2COOH$ (Phenylacetic acid): The phenyl group ($C_6H_5$) also exerts an electron-withdrawing inductive effect ($-I$ effect), which stabilizes the conjugate base more than a simple alkyl group, but less effectively than the highly electronegative Bromine atom.

Compound (B) $CH_3COOH$ (Acetic acid): The methyl group ($CH_3$) is an electron-donating group ($+I$ effect). As mentioned in the passage, electron-donating substituents tend to decrease acidic strength because they destabilize the conjugate base.

Compound (A) $CH_3CH_2OH$ (Ethanol): This is an alcohol. The passage explicitly states that carboxylic acids are more acidic than alcohols because of the greater resonance stabilization of the carboxylate ion compared to the alkoxide ion.