When the pH decreases from 6 to 3, the hydrogen ion, H+, increases by what?

pH decreases as the hydrogen ion concentration increases.

Explanation:

When there is a decrease in pH, that is pH decreases from 6 to 3 then the acidity increases.

That is the pH is between 1 to 7 then it is acidic

When the pH is 7 then it is neutral

When the pH is between  7 to 14 then it is basic

As the H⁺ ion concentration increases, then the pH value decreases, here pH decreases from 6 to 3.

So the concentration of Hydrogen ion increases, pH decreases.

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.