162 



GENERAL SCIENCE 



QUESTIONS AND EXERCISES 



1. What is the difference between a compound and a mixture 

 of elements ? 



2. Is the air a mixture of gases or a compound ? 



3. Give the approximate composition of the air. 



4. Compare the vertical extent of the atmosphere with the 

 height of the highest mountain. 



5. Why does a person's nose bleed while climbing a high moun- 

 tain? 



6. What causes a balloon to ascend ? 



7. Which is the heavier, a balloon ascending or an equal volume 

 of air ? 



8. Which is the heavier, a bicycle tire pumped full of air or an 

 empty one ? Swimming wings full of air or empty ones ? 



9. What is the approximate air pressure in your schoolroom? 

 Is it less than at sea level ? Why ? 



10. Which is the greater, the downward pressure of the mercury 

 in a barometer or the pressure of the ( 



air around the barometer ? 



11. When you drink a liquid 

 through a tube, what causes the 

 liquid to rise? 



12. What are barometers used for ? 



13. What causes winds? Which 



bring rain? Do winds carry A 



winds 



heat? 



14. 



I 



B 



Explain the formation of dew. 

 Make some dew form by placing very 

 cold water or ice in a metal vessel. 



15. What do isobars and isotherms 

 indicate on weather maps? 



16. Explain the meaning of the 

 words, "high" and "low" on weather maps. 



17. What kind of weather usually accompanies a "high" ? "low"? 



CHALKED PLATES from which 

 the cast is made for print- 

 ing the Weather Maps. 

 A, is the blank form; B, 



after the map characters have 



been cut out of the chalk 



down to the steel. 



