PART II 



(Omit one group. Each question counts 10.) 

 GROUP A 



6. Starting with generally available raw materials, how should you prepare 



four of the following: (i) dry calcium chloride, (2) crystals of ferrous 

 sulphate, (3) bromine, (4) dry nitrous oxide, (5) crystals of silver nitrate ? 



7. (a) How should you determine quantitatively the percentage of oxygen in 



the air ? 



(b) Describe experiments involving chemical change sufficient to distinguish 

 between three of the four following pairs: (i) lead acetate and lead 

 carbonate, (2) calcium chloride and zinc chloride, (3) concentrated and 

 dilute sulphuric acid, (4) hydrogen peroxide and water. 



GROUP B 



8. (a) A compound of the elements A and B contains 45 parts of A and 28 parts 



of B by weight. If another compound of the same elements exists, 

 what quantities of B should you expect to find combined with 45 parts 

 by weight of A ? State the law upon which your conclusion is based. 

 (b) According to the theory of electrolytic dissociation, what takes place 

 when dilute solutions of an acid and a base are mixed ? 



9. (a) What are the reasons for believing that the hydrogen molecule contains 



two atoms ? 



(b) What is a reversible reaction? Give an illustrative equation. Under 

 what circumstances do such reactions go to completion ? 



GROUP C 



10. Mention one useful property of each of ten of the following substances, 



and give in each case one useful application based upon that property: 

 hydrogen, chlorine, alum, zinc chloride, ferric oxide, Pb 3 O 4 , copper sulphate, 

 HgCl, HgCl 2 , silver nitrate, sulphur dioxide, potassium nitrate. 



11. (a) Name three general classes of foods and show in which class or classes 



each of the following should be placed: butter, lean meat, milk, wheat 

 bread, corn starch, egg. 



(b) (i) Why is a superphosphate used in preference to normal phosphate as a 

 fertilizer ? (2) Why is iron made in a blast furnace while zinc is made 

 in a retort? (3) Why is sulphuric acid used in preference to hydro- 

 chloric in making nitric acid ? (4) Why should sea-water not be used 

 in a steam boiler ? (5) What are the chief products of the distillation 

 of soft coal ? 



