Answer:
Acid rain refers to any form of precipitation that contains higher than normal levels of hydrogen ions (giving it a low pH, and thus, making it more acidic). Acid rain is generally caused by sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions; these emissions can either be from natural sources (e.g. Volcanoes) or human-related ones (e.g. factory combustion). Therefore, the acid in acid rain is either sulfuric acid, or nitric acid.
First answer by Legendofme. Last edit by Legendofme. Contributor trust: 4 [recommend contributor recommended]. Question popularity: 1 [recommend question].