146 FIRST YEAR COURSE IN GENERAL SCIENCE 



7. Why is prompt action with a limited amount of water more suc- 

 cessful in extinguishing a fire than a larger amount of water after the 

 fire is well started? 



8. Why does not the carbon dioxide formed by combustion extin- 

 guish the flames which produce it? 



9. If some kerosene were spilled and burning, why would sand be 

 a better extinguisher than water? 



10. Compare suffocation with the process of putting out a fire. 



11. Why is oxidation the commonest change in matter? Give three 

 illustrations of oxidation not mentioned in the text. 



