An unknown solution has a pH of 7.2. Which of these chemicals is likely to cause the greatest decrease in the pH of the solution when added to the solution? HF KOH NH3 HNO3

HNO₃.

Explanation:

It is known that acids decrease the pH of the solution, while bases increase the pH of the solution.

So, HF and HNO₃ decrease the pH of the solution as they produce H⁺ in the solution.

While, KOH and NH₃ increase the pH of the solution as they produce OH⁻ in the solution.

HNO₃ will decrease the pH of the solution greater than HF.

Because HNO₃ is strong acid that decomposes completely to produce H⁺ more than the same concentration of HF that is a weak acid which does not decomposed completely to produce H⁺.