REVIEW QUESTIONS 111 



3. How is carbon dioxide harmful and in what way 

 is it helpful? 



4. What are some of the oddities of solution? 



5. Name all the uses of water. Which one is the 

 most important? 



6. Why is soft water cheaper to use than hard 

 water although the same price is paid for each? 



7. How can you prove that plants obtain water 

 from below the surface of the ground? How do they do 

 it? 



8. Why is wet earth heavier than dry earth? 

 Which kind of earth would be heavier when wet, a fine 

 earth or a coarse earth? Explain. 



9. Why do farmers break up the soil so that it is 

 fine, before they plant? 



10. Why do our feet become wet when we walk on 

 the wet sidewalk? 



