Well, I think it's mainly for photosynthesis and gas exchange. A leaf is normally flat, light, and thin, so that the sunlight can get to the chloroplasts in the cells.
Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
