Chemicals in the air can combine with rain to produce acid rain, which is harmful to the environment. Which of these is most likely to be the pH of acid rain?
Normal rain has a pH between 5.0 and 5.5, which is slightly acidic on the pH scale. Acid rain on the other hand has an average pH of 4.0, much more acidic than your average rain.
Therefore, the most likely pH of acid rain would be 4.0.
