Which of the following best represents the composition of an aqueous solution of a strong acid and a strong base?

• A. The solution contains undissociated molecules of the acid and base, with few ions.
• B. Only H_2O molecules are present, with no ions.
• C. The solution contains H_3O^+ and OH^- ions in equal concentrations, along with H_2O molecules.
• D. The solution contains only H_3O^+ ions and H_2O molecules.

Answer: (C)

Verified step by step guidance

1. Recall that strong acids and strong bases completely dissociate in aqueous solution, meaning they break apart fully into their ions.
2. Understand that when a strong acid (like HCl) dissolves in water, it donates protons (H^+) to water molecules, forming hydronium ions (H_3O^+).
3. Similarly, a strong base (like NaOH) dissociates completely to produce hydroxide ions (OH^-) in solution.
4. When equal amounts of a strong acid and a strong base are mixed, the H_3O^+ ions from the acid and the OH^- ions from the base neutralize each other, but both ions are still present in equal concentrations at equilibrium in the solution.
5. Therefore, the solution contains hydronium ions (H_3O^+), hydroxide ions (OH^-), and water molecules (H_2O), reflecting a neutralized but ion-containing aqueous solution.