Acid rain is caused by the pollution of environment by

1. Acid rain refers to precipitation (rain, snow, fog, etc.) that is unusually acidic, meaning it possesses elevated levels of hydrogen ions (low pH). Natural rain is slightly acidic (pH around 5.6) due to dissolved carbon dioxide forming carbonic acid. 2. Anthropogenic acid rain is primarily caused by emissions of sulphur dioxide (SO2) and nitrogen oxides (NOx, which includes nitrous oxide N2O, nitrogen monoxide NO, and nitrogen dioxide NO2) into the atmosphere. 3. These gases, released mainly from burning fossil fuels in power plants, industries, and vehicles, react with water, oxygen, and other chemicals in the atmosphere to form sulfuric acid (H2SO4) and nitric acid (HNO3). 4. These strong acids then fall to the Earth dissolved in precipitation, causing environmental damage. 5. While carbon dioxide contributes to natural rain acidity, it's not the primary cause of the harmful acid rain pollution. Carbon monoxide and ozone are pollutants but do not directly form the strong acids characteristic of acid rain. Atmospheric nitrogen (N2) is largely unreactive. 6. Therefore, the key pollutants responsible for acid rain are nitrous oxide (representing nitrogen oxides) and sulphur dioxide.