The H3O in a solution is 12.57.
Step-by-step explanation:
The hydronium ion concentration can be found from the pH by the reverse of the mathematical operation employed to find the pH.
pOH = -log[H3O]
pOH = -log(3.75x10^-2)
= 1.43
Now, pH = 14 - 1.43
= 12.57
The H3O in a solution is 12.57.