What is the primary difference between a strong acid and a weak acid?

The primary difference between a strong acid and a weak acid lies in their ability to dissociate in solution. A strong acid fully dissociates in water, which means that it breaks down completely into its ions. This dissociation results in a higher concentration of hydrogen ions (H⁺) in solution, making the solution highly acidic.

In contrast, weak acids do not completely dissociate; they only partially break down into ions, leading to a lower concentration of hydrogen ions in the solution. As a result, weak acids are characterized by a more moderate pH compared to strong acids.

The other options do not accurately represent the behavior of acids in solution. While weak acids do not fully dissociate, suggesting they only partially ionize, and both types of acids do not completely dissociate at the same extent as each other. Similarly, the corrosive nature of an acid is not solely defined by its strength; both strong and weak acids can vary widely in their corrosivity depending on their concentration and chemical structure. Thus, the correct choice emphasizes the complete dissociation characteristic of strong acids in solution.