Higher the hydronium ion concentration _________ is the pH of the solution.

Concept:

The Hydronium ion is formed when an acid dissociates in aqueous medium:

H⁺ (from acid) + H₂O → H₃O⁺ ( Hydronium ion)

Larger Hydronium ion concentration simply means that the acid is more dissociated in the medium.

Application:

The acidity of solution is inversely related to its pH.

As hydronium ion concentration increases, the solution becomes more acidic.

Hence the pH of the solution decreases.