Chemistry - GOC Question with Solution | TestHub

Carboxylic acid is stronger acid than $-{\mathrm{NH}}_3$, therefore, $X$ is the strongest acid. Since $-\mathrm{COOH}$ has $-I$-effect which decreases with distance, therefore, $-I$-effect is more pronounced on $Z$ than on $Y$. As a result, $Z$ is more acidic than $Y$. Thus, overall order of decreasing acidic strength is $X>Z>Y$.