Acid rain is caused by the pollution of the environment by nitrous oxide (NOx) and sulfur dioxide (SO2). These pollutants are released into the atmosphere mainly through human activities such as burning fossil fuels, industrial processes, and transportation.

1. Nitrous Oxide (NOx):
- Nitrous oxide is produced by the combustion of fossil fuels, primarily in vehicles and power plants.
- It is also released by agricultural activities, such as the use of nitrogen-based fertilizers and the burning of crop residues.
- Nitrous oxide reacts with other compounds in the atmosphere to form nitric acid (HNO3), which is a major component of acid rain.

2. Sulfur Dioxide (SO2):
- Sulfur dioxide is mainly emitted by the burning of fossil fuels, particularly coal and oil, in power plants and industrial processes.
- It is also released during the extraction and processing of metals and the production of certain chemicals.
- Sulfur dioxide reacts with other substances in the atmosphere, such as oxygen and water vapor, to form sulfuric acid (H2SO4), which is another major component of acid rain.

3. Formation of Acid Rain:
- Once nitrous oxide and sulfur dioxide are released into the atmosphere, they undergo chemical reactions with other compounds.
- These reactions result in the formation of nitric acid and sulfuric acid, which then combine with water vapor in the atmosphere to form acid rain.
- Acid rain refers to any form of precipitation, such as rain, snow, or fog, that has a pH level below 5.6 (slightly acidic) due to the presence of these acids.

Impact of Acid Rain:
- Acid rain has detrimental effects on the environment, including damage to forests, lakes, and aquatic ecosystems.
- It can leach essential nutrients from the soil, making it difficult for plants to grow and thrive.
- Acid rain can also lead to the acidification of lakes and rivers, which can harm fish and other aquatic organisms.
- Additionally, it can corrode buildings, statues, and infrastructure made of limestone or marble.

In conclusion, acid rain is primarily caused by the pollution of the environment by nitrous oxide and sulfur dioxide. These pollutants are released into the atmosphere through human activities, such as the burning of fossil fuels and industrial processes. The chemical reactions of these pollutants with other compounds in the atmosphere result in the formation of nitric acid and sulfuric acid, which combine with water vapor to form acid rain.