Add 0.2mol of Hydrochloric Acid (H) to water to make 4 liter of solution at 25°. Please determine the pH of the solution at equilibrium state. If we only add 10⁻⁷mol of H into the water and the volume of the solution keeps unchanged, what is the pH of the solution now? Note that the ionization equilibrium constant of H is KH=10₃.