Question

$p{K}_a$ value of four acids are given below. The strongest acid is:

• A. $4.0$
• B. $3.5$
• C. $2.5$
• D. $2$

Answer 1

Answer: (D)

$2$

As we know,

Strength of acid $\propto K_a$ or $\propto \frac{1}{p{K}_a}$

Hence acid with lowest $p{K}_a$ value $\left(2.0\right)$ will be strongest.