Acid rain can do serious damage to the environment as well as human health. Acidity is measured according to thepH scale. Pure water has a pH of 7, which is considered neutral. A pH less than 7 indicates anacidicsolution, and a pH higher than 7 indicates abasicsolution. (Lye and baking soda solutions are very basic; vinegar and lemon juice are acidic.) An increase of 1 on the pH scale causes acidity to be multiplied by a factor of 1/10. Equivalently, a decrease of 1 on the pH scale causes acidity to be multiplied by a factor of 10. If rainfall has a pH of5, how many times as acidic as pure water is it? (It is worth nothing that most acidic rain in the United States has a pH of about 4.3).