WATER 107 



change. As the heat is used, of course, the temperature 

 must fall in those objects from which the heat was ab- 

 stracted. 



QUESTIONS 



1. Why will clothes dry better on a windy day than on a still 

 one? 



2. Why are large shallow pans used in making maple sirup? 



3. What is the temperature of deep water? Does it change 

 much in summer and winter? 



4. If ice is 0.92 as heavy as water, what fractional part of the 

 ice will float out of water? 



5. Is the freezing of water a physical or chemical change? 



6. Why is it difficult to cook vegetables at Quito ? 



7. Why are vessels often broken by freezing water? 



8. If ice were heavier than water, would there be any disastrous 

 results? 



9. What are the essential differences between oxygen and 

 hydrogen ? 



10. Name three chemical changes. Six physical changes. 



11. When a pan is over a gas stove with the flame burning low, 

 water forms on the surface of the pan next the flame. Why? 



12. Can you see steam? What is it we see and call steam? 



13. Is the ocean water more dense than the water of Lake 

 Erie? Why? 



14. When we heat copper sul-phate crystals, we may hear little 

 cracking sounds. What causes these sounds? 



