Which of the following is not a characteristic of a strong acid in the context of acids and bases?

• A. Completely dissociates in water
• B. Has a low $pH$ value
• C. Has a high $pKa$ value
• D. Produces a high concentration of $H^{+}$ ions

Answer: (C)

Verified step by step guidance

1. Understand the concept of a strong acid: A strong acid is one that completely dissociates in water, meaning it releases all of its hydrogen ions (H⁺) into the solution.
2. Recognize that a strong acid will produce a high concentration of H⁺ ions in solution, which is a key characteristic.
3. Recall that the pH scale is a measure of the concentration of H⁺ ions in a solution. A strong acid, having a high concentration of H⁺ ions, will have a low pH value.
4. Understand the relationship between pKa and acid strength: pKa is the negative logarithm of the acid dissociation constant (Ka). A lower pKa value indicates a stronger acid because it implies a higher degree of dissociation.
5. Identify the characteristic that does not align with a strong acid: A high pKa value suggests a weaker acid, as it indicates less dissociation and a lower concentration of H⁺ ions in solution.