Question

Which of the following acid has highest $pKa$ value?

• A. $O_{2}NC{H}_{2}COOH$
• B. $NCC{H}_{2}COOH$
• C. $FC{H}_{2}COOH$
• D. $C_6{H}_{5}C{H}_{2}COOH$

Answer 1

Answer: (D)

Acidic strength $\alpha \frac{1}{pKa}\alpha$ stability of conjugate base. $C_5{H}_{5}C{H}_{3}COOH$ is weakest acid among all so has highest $pKa$ value.