Pay attention to the calculation of PH: the acid solution is calculated by the concentration of hydrogen ions, and the alkaline solution is calculated by the concentration of hydroxyl ions (then converted into the concentration of hydrogen ions).

In the NaOH solution of 1LPH= 10, the concentration of hydroxide ion is 10-4 mol/L, and the concentration of hydroxide ion is 10-4 mol. When diluted to 10L with water, the hydrogen ion concentration becomes10-5 mol/l.

Because all hydrogen ions are ionized by water, and the ionization of water is promoted when it is diluted, there are more ionized hydrogen ions, so it cannot be considered that hydrogen ions are diluted 10 times.