How does a strong acid behave in solution compared with a weak acid?

• A. It completely ionises to give H+ ions in solution; the weak acid only partially ionises
• B. It changes color but the weak acid does not
• C. It increases the solution’s density more than the weak acid
• D. It forms covalent bonds with the solvent rather than ionising

Answer: (A)

Strong acids in water dissociate completely, releasing all the protons as H+ (usually existing as H3O+ in solution). A weak acid only partially ionizes, so there’s an equilibrium with undissociated molecules. Because the strong acid makes many more ions, it creates a higher [H3O+], giving a much lower pH and better electrical conductivity compared with a weak acid at the same concentration. Things like color change or density aren’t reliable indicators of acid strength, and acids don’t generally form covalent bonds with the solvent in this context—the key idea is ionization in solution.