Final answer:
The concentration of H+ ions between a pH of 3 and a pH of 2 differs by a factor of 10.
Step-by-step explanation:
The concentration of H+ ions between a pH of 3 and a pH of 2 differs by a factor of 10. According to the pH scale, each pH unit represents a 10-fold difference in the concentration of hydrogen ions.
Therefore, since the pH decreases from 3 to 2, the concentration of H+ ions is 10 times greater at pH 2 compared to pH 3.