What formula can be used to calculate [H30+]?

A. [H3O+] = log (OH-)

B. [H3O+] = 1 x 10 [-OH-]

C. [H3O+] = antilog (-pH)

D. [H3O+] = [H3O+][ OH-]

I think the correct answer is option C. The formula that can be used to determine the concentration of hydronium ions, [H3O+], would be [H3O+] = antilog (-pH). This is from the expression of pH which is a measure that is used for the acidity of a certain solution based on the hydronium ion concentration in the solution. It is expressed as pH = - log [H3O+]. Manipulating the equation so that [H3O+] is left on one side would lead us to the same expression as given in option C.

pH = - log [H3O+]

-pH = log [H3O+]

10^-pH = 10^log [H3O+]

10^-pH = [H3O+]

where 10^x is the same as antilog of x.

[H3O+] = antilog (-pH)