* pH Scale: The pH scale measures the acidity or alkalinity of a solution. A lower pH indicates higher acidity, while a higher pH indicates higher alkalinity (or basicity).

* Neutralization: Neutralization occurs when an acid reacts with a base. This reaction results in the formation of salt and water.

* Hydrogen Ions: Acids contain hydrogen ions (H+) which contribute to their acidity.

* Hydroxide Ions: Bases contain hydroxide ions (OH-), which contribute to their alkalinity.

* Neutralization Reaction: When an acid and base react, the H+ ions from the acid combine with the OH- ions from the base to form water (H2O). This reaction effectively removes H+ ions from the solution, decreasing the acidity.

Therefore, as the acid is neutralized, the concentration of H+ ions decreases, resulting in an increase in pH towards neutrality (pH 7).