258 GENERAL SCIENCE 



5. Why do we paint iron building frames? 



* 6. Name ten of the most useful elements. 



7. Name four uses of cast iron. Three uses of wrought iron. 



8. How is chlorine used in warfare? 



9. Arrange iron, lead, zinc, sodium, gold, aluminum, copper, 

 silver, and platinum in order of their densities. 



10. What are some of the commercial uses of gold? Lead? 

 Tin? Zinc? Copper? Sulphur? Aluminum? 



11. What causes the hardness of razor steel? 



12. What kind of iron would you use for bicycle pedals? Why? 



