question_answer

The carboxylic acid of least strength among the following is

A)  p-nitrobenzoic acid

B)  p-methylbenzoic acid

C)  p-chlorobenzoic acid     

D)  p-methoxybenzoic acid

Correct Answer: D

Solution :

                Higher the tendency of an acid to release a proton, higher is the acidic strength. Presence of electron  releasing  group  such  as \[OC{{H}_{3}},C{{H}_{3}}\]etc (\[OC{{H}_{3}}\]is more electron releasing than\[C{{H}_{3}}\]group) increases the electron density of the carboxylate anion. Consequently, the anion becomes unstable and the release of proton becomes difficult. Thus, weaker is the acid. Hence, p-methoxy benzoic acid