134 APPLIED SCIENCE 



6. Why is hydrogen selected to fill balloons and some air-ships? 



7. Give the characteristics of a metal. 



8. What is the difference between a metallic and a non-metallic 

 element? 



9. What is analysis? Synthesis? Metallurgy? 



10. What is the symbol for water? 



11. How do we know what the definite symbol for water is? 



12. What is the value of a chemical equation? 



13. What is the valence of an element? 



14. What is chemical action? 



16. What is the difference between physical action and chemi- 

 cal action? 



16. What is the molecular weight of hydrochloric acid? 



17. Write the equation for "killing" (neutralizing) muriatic 

 (hydrochloric acid) and zinc. 



18. How much zinc chloride will be formed from 4 oz. of zinc? 



19. Describe the properties of oxygen; hydrogen. 



