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

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.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

a is the correct answer