The ionization constant Ka given is not relevant for hydrochloric acid, as HCl is a strong acid and dissociates completely in water. Therefore, we do not need to use the ionization constant to calculate the pH of the solution.To find the pH of a 0.1 M HCl solution, we can use the formula:pH = -log10[H+]Since HCl is a strong acid and dissociates completely, the concentration of H+ ions in the solution will be equal to the concentration of HCl, which is 0.1 M.pH = -log10 0.1 pH = 1The pH of a 0.1 M solution of hydrochloric acid HCl is 1.