Question

Compound which has the highest $p{K}_a$ is:
[0.77 Mark]

• A. $\text{HF}$
• B. $\text{HCl}$
• C. $\text{HBr}$
• D. $\text{HI}$

Answer 1

The correct option is A $\text{HF}$

We know that, more is the acidic strength, lesser is the $pKa$ value and oppositely lesser is the acidic strength more is the $pKa$ value. The acidic strength increases in the order $HF<HCl<HBr<HI$ since bond dissociation energy decreases in this order. Thus $HF$ has the highest $pKa$ value.