What Directly Relates to the Acidity of a Solution

Question

What directly relates to the acidity of a solution?
A) concentration of bound anions
B) concentration of free electrons
C) concentration of bound protons
D) concentration of free protons

Accepted Answer

The acidity of a solution is directly related to its concentration of free protons (H+ ions). The more free protons present, the more acidic the solution is.