Available Answers

1. 1.

   Describe the composition of a sample of clean air.

2. 2.

   Describe two methods of removing insoluble impurities from water.

3. 3.

   Describe the layers of the earth's atmosphere.

4. 4.

   How can you prove that air exerts pressure?

5. 5.

   How is raw water treated in a city's water supply system?

6. 6.

   Describe the process of distillation.