Which of the following is not a characteristic of a strong acid?

• A. Has a low $pKa$ value
• B. Completely ionizes in solution
• C. Has a high $pH$ value
• D. Donates protons easily

Answer: (C)

Verified step by step guidance

1. Understand the definition of a strong acid: A strong acid is one that completely ionizes in solution, meaning it donates all its available protons (H⁺ ions) to the solution.
2. Recall the relationship between pKa and acid strength: A low pKa value indicates a strong acid because it signifies that the acid dissociates well in solution, releasing protons easily.
3. Consider the pH value: Strong acids have a low pH value because they increase the concentration of H⁺ ions in the solution, making it more acidic.
4. Evaluate the given characteristics: 'Has a low pKa value' and 'Completely ionizes in solution' are both characteristics of strong acids.
5. Identify the incorrect characteristic: 'Has a high pH value' is not a characteristic of a strong acid, as strong acids typically have low pH values due to their high concentration of H⁺ ions.