what is acid rain?

Acid rain is rain that’s acidic. This means it has been mixed in with pollutants... resulting in rain that has more positive hydrogen (h+) ions then normal.  The more h+ ions created in a substance, the more acidic the substance becomes.  The more acidic a substance is, the lower it is on the pH scale.  7 is neutral.  Above 7 is basic and below is acidic.  Rain has to have a pH of less then 5, to be considered acid rain.

Here is a pH scale for you to compare acid rain with other substances

.