Which statement correctly describes strong acids?

• A. Acids that ionize partially in water
• B. Acids that ionize completely in water to form H3O+
• C. Acids that do not ionize
• D. Acids that donate protons

Answer: (B)

Strong acids are defined by how completely they ionize in water. When a strong acid dissolves, it donates its proton to water to form hydronium ions (H3O+) so completely that essentially all of the acid molecules exist as ions. In equation form, the dissociation lies far to the right, meaning [H3O+] becomes very large and almost no undissociated acid remains. This is why their solutions are highly acidic and why their dissociation constants are effectively very large.

The statement that acet would ionize only partially describes weak acids, not strong ones. Saying it does not ionize at all would describe something that behaves like a nonacid or an insoluble substance, not a strong acid. While acids do donate protons, that alone does not define strength; strength is about how fully the acid ionizes in solution to form hydronium ions.