Under Arrhenius theory, which statement is true?

• A. Bases produce H+ in water
• B. Acids do not ionize in water
• C. Salts are formed by acid-base reactions
• D. Acids produce H+ in water

Answer: (D)

Arrhenius theory defines acids as substances that increase the concentration of H+ in aqueous solution. In water, the emitted proton doesn’t stay free; it bonds with a water molecule to form hydronium (H3O+). So saying acids produce H+ in water reflects this defining behavior of Arrhenius acids. The statement about bases producing H+ would be incorrect because bases increase OH− in solution. The claim that acids do not ionize in water is the opposite of Arrhenius chemistry, since their ionization to release H+ is exactly what acid behavior in water is about. The statement that salts are formed by acid-base reactions is true in general, but it doesn’t specify the aqueous proton-donor property that Arrhenius defined, which is why the acid-in-water description is the best direct answer.