HClO4 perchloric acid is a strong acid, which means it completely dissociates in water. When it dissociates, it releases H+ ions. The concentration of H+ ions in the solution will be equal to the concentration of the HClO4 solution.In this case, the concentration of HClO4 is 0.1 M, so the concentration of H+ ions will also be 0.1 M.The pH of a solution is calculated using the formula:pH = -log10[H+]where [H+] is the concentration of H+ ions in the solution.For this problem:pH = -log10 0.1 pH = - -1 pH = 1So, the pH of a 0.1 M solution of HClO4 at 25C is 1.