Answer:
The release of sulfur dioxide and nitrogen oxides into the air.
Step-by-step explanation:
Your question does not add any specific guidelines for answers so I'll just cover the basics.
Sulfur dioxide (or SO2) and nitrogen oxides (NOX) are released into the air from powerplants after fossil fuel is burnt. These gases are admitted into the atmostphere, and get carried by air currents. They react with other chemicals and create sulfuric and nitric acids. They then mix with water before falling to the ground in precipitation, i.e. acid rain.
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