The formation of acid rain primarily involves the emission of sulfur dioxide SO2 and nitrogen oxides NOx into the atmosphere, which then react with water, oxygen, and other chemicals to form acidic compounds. These compounds then fall to the ground in the form of rain, snow, fog, or dry deposition.1. Sulfur dioxide SO2 emissions: The main source of SO2 is the burning of fossil fuels, such as coal and oil, in power plants and industrial processes. The chemical reactions involved in the formation of acid rain from SO2 are: SO2 + H2O H2SO3 sulfurous acid 2SO2 + O2 + 2H2O 2H2SO4 sulfuric acid 2. Nitrogen oxides NOx emissions: NOx is mainly produced from automobile exhausts and industrial combustion processes. The chemical reactions involved in the formation of acid rain from NOx are: NO + O2 NO2 nitrogen dioxide NO2 + H2O HNO3 nitric acid When these acidic compounds fall to the ground, they can lower the pH levels of water bodies and soils in affected areas. The pH scale ranges from 0 to 14, with 7 being neutral. Acidic substances have a pH below 7, while alkaline substances have a pH above 7. Normal rainwater has a pH of around 5.6 due to the presence of dissolved carbon dioxide, which forms carbonic acid H2CO3 .Acid rain typically has a pH of 4.2 to 4.4, making it more acidic than normal rainwater. When acid rain enters water bodies such as lakes, rivers, and streams, it can lower their pH levels, making the water more acidic. This can have harmful effects on aquatic life, particularly for species that are sensitive to changes in pH, such as fish and other aquatic organisms.Similarly, acid rain can also affect soil pH levels. Soils have a natural buffering capacity, which means they can neutralize a certain amount of acidity. However, if the input of acidic compounds from acid rain is too high, the soil's buffering capacity can be overwhelmed, leading to a decrease in soil pH. This can have negative impacts on plant growth and nutrient availability, as well as on soil-dwelling organisms.In summary, the main chemical reactions involved in the formation of acid rain are the oxidation of sulfur dioxide and nitrogen oxides, which then react with water to form acidic compounds. These compounds can lower the pH levels of water bodies and soils, potentially causing harm to aquatic life, plants, and soil organisms.