Question

Based on the entries in the following table, which element is most commonly bonded to the acidic hydrogen? table some weak acids in water at 25 ∘c

Answer 1

According to picture below, C₆H₅O⁻ is most commonly bonded to the acidic hydrogen, because it has smallest Ka (the acid dissociation constant).
Chemical reaction: C₆H₅OH(aq) ⇄ C₆H₅O⁻(aq) + H⁺(aq).
Ka = [C₆H₅O⁻] · [H⁺] / [C₆H₅OH]. 
Equolibrium concentration of hydrogen ions is very low in water solution of phenol.

Answer 2

The Correct is C₆H₅O⁻ : It is the most commonly bonded to the acidic hydrogen , and O2 is the most element bonded to the acidic hydrogen.

The explanation:

According to the table below we can see that the Ka ( the acid dissociation constant) for the Phenol is the smallest one.

when the Ka expression for this chemical reaction:

C₆H₅OH(aq) ⇄ C₆H₅O⁻(aq) + H⁺(aq)

is

Ka = [C₆H₅O⁻] · [H⁺] / [C₆H₅OH]

So, the water solution of the phenol has a very low equilibrium concentration of H ions [H+] , So C₆H₅O⁻ is the element which most commonly bonded to the acidic hydrogen.