Which of the following statements is not true about the acidity of $\mathrm{carboxylic} \mathrm{acids}$?

• A. The presence of electron-withdrawing groups increases the acidity of $\mathrm{carboxylic} \mathrm{acids}$.
• B. $\mathrm{Carboxylic} \mathrm{acids}$ are generally stronger acids than $\mathrm{alcohols}$.
• C. The acidity of $\mathrm{carboxylic} \mathrm{acids}$ is due to the resonance stabilization of their conjugate base.
• D. $\mathrm{Carboxylic} \mathrm{acids}$ cannot donate protons in aqueous solutions.

Answer: (D)

Verified step by step guidance

1. Identify the key functional group in carboxylic acids, which is the carboxyl group (-COOH). This group is responsible for the acidic properties of carboxylic acids.
2. Understand that the acidity of carboxylic acids is primarily due to the ability of the carboxyl group to donate a proton (H+) to form a carboxylate ion (RCOO-).
3. Recognize that the carboxylate ion is resonance-stabilized, meaning the negative charge can be delocalized over the two oxygen atoms, which increases the stability of the conjugate base and thus the acidity of the acid.
4. Consider the effect of substituents on the acidity: Electron-withdrawing groups (such as -NO2, -Cl) increase acidity by stabilizing the negative charge on the carboxylate ion, while electron-donating groups (such as -CH3, -OCH3) decrease acidity.
5. Evaluate the statement 'Carboxylic acids cannot donate protons in aqueous solutions.' This is incorrect because carboxylic acids are known to donate protons in aqueous solutions, which is a fundamental property of acids.