'''Acid rain ''' is [[rain ]] that is more acidic [[acid]]ic than in its natural state, and is usually consider considered to be have a pH of less than 5. (Natural rain water is slightly acidic due to the presence of dissolved [[carbon dioxide]]). Acid rain forms when [[sulphur sulfur dioxide]] dissolves in [[water]] to make [[sulphurous sulfurous acid]]. The [[sulphur sulfur dioxide]] can also be oxidized to [[sulphur sulfur trioxide]] and form [[sulfuric acid]] upon reaction with [[water]] .
Acid rain can cause damage to structures and statues, and also plant life. (For example , the [[Black forest]] of [[Germany]] has been heavily damaged by acid rain.) The combined action of carbonic, sulphuric and nitric acid can dissolve limestone statues on account of a neutralisation reaction. [[Category:Environment]][[categoryCategory:environmentAcids]]