The addition of an acid like HCl to an aqueous solution (pure water) would result in:

• A. An increase in pH only.
• B. Both the release of H⁺ and an increase in pH.
• C. Both the release of H⁺ and a decrease in pH.
• D. The release of H⁺ into the solution only.
• E. A decrease in pH only.

Answer: (C)

Verified step by step guidance

1. Understand the nature of hydrochloric acid (HCl) as a strong acid, which dissociates completely in water to release hydrogen ions (H⁺).
2. Recognize that the release of H⁺ ions into the solution increases the concentration of hydrogen ions in the water.
3. Recall the pH scale, where a lower pH value indicates a higher concentration of H⁺ ions, meaning the solution becomes more acidic.
4. Consider the effect of increased H⁺ concentration on the pH: as H⁺ concentration increases, the pH decreases.
5. Conclude that the addition of HCl to pure water results in both the release of H⁺ ions and a decrease in pH, making the solution more acidic.