Answer:
as acid is added, the pH of a solution decreases and the hydronium acid concentration increases.
Explanation:
the pH & hydronium ion concentration of solution are inversely related by the equation pH=-log(H+).
Acids are hydronium donors, so when we add an acid to a solution, the hydronium in it will decrease.
Using the above equation, we can see that the more hydronium is added, the less the pH will be since there's a negative sign.