The acidity of carboxylic acid is determined by the nature of the alkyl group attached and the substiuent present on it. It is affected mainly by the inductive effect of the substituent and its position with respect to the -COOH group. Electron-donating substituent tends to decrease the acidic strength whereas electron-withdrawing substituent tends to increase acidic strength. The acidic strength of aromatic carboxylic acid on the other hand depends upon both the inductive and resonance effects of the substituents.
Which of the following would be expected to be most highly ionized in water ?
A. `ClCH_(2)CH_(2)CH_(2)COOH`
B. `CH_(3)CHClCH_(2)COOH`
C. `CH_(3)CH_(2)C"C"l_(2)COOH`
D. `CH_(3)CH_(2)CHClCOOH`
