Read the paragraph, and then complete the model. Fossil fuels are substances that can be burned to produce energy. The burning o
f fossil fuels releases certain gases into the air. These gases combine with other chemicals in the air to form substances called acids. When trees on the top of mountains are exposed to clouds that contain these acids, the acids remove substances from the trees that help the trees fight against harmful insects. Fill in the blanks with the correct sphere names to model how spheres are connected when fossil fuels are burned. → ββββ
