Part II 



(Omit one group. Each question counts 10.) 



Group A 



6. Answer five of the following: {a) How would you make ferrous chloride 



from ferric chloride ? {b) Ferric chloride from ferrous chloride ? (c) White 

 lead from lead ? {d) Sodium sulphite from sodium hydroxide ? (e) Sodium 

 hypochlorite from sodium hydroxide ? (/) Alum crystals from aluminum 

 sulphate ? 



7. Mention very briefly any means of identifying with certainty each of the 



following gases: hydrogen, nitrogen, carbon dioxide, sulphur dioxide, nitrous 

 oxide, chlorine, carbon monoxide, hydrogen sulphide, oxygen, ozone. 



Group B 



8. (a) Ten liters of a gas whose formula is C2H6O are completely burned in 



oxygen. How many liters of oxygen gas are required for its complete 

 combustion ? How many liters of carbon dioxide should result ? All 

 volumes are measured under the same conditions of temperature and 

 pressure. 

 {h) If the temperature of a gas enclosed at an initial pressure of one atmos- 

 phere is decreased from 37° C. to 27° C. without change in volume, 

 what will be the final value of the pressure ? 



9. (a) What classes of substances are electroly tically dissociated ? What is the 



effect of dilution on the degree of dissociation of the substance ? How 

 may the degree of dissociation be diminished without changing mate- 

 rially the volume of the solution ? 

 {b) Show how the electric current is conveyed through a solution of CUSO4, 

 and indicate the reactions that take place at the poles. 



Group C 



10. (a) Mention one important industrial process depending on each of the 



following phenomena respectively: reduction, catalysis, crystalliza- 

 tion, electrolysis. 

 (6) State what impurities render water unfit for (1) drinking purposes, 

 (2) steam boilers, (3) laundries; and outline a different practical 

 method adapted to improving the water in each case. 



11. Answer four of the following questions: 



(a) Explain the cleansing action of soaps. Of what substances are washing 



powders likely to be composed ? 

 {b) Describe one method of converting pig iron into steel, 

 (c) Explain upon a chemical basis the use of ozone in the purification of water. 

 {d) Name two products of commercial importance that can be obtained, by 



chemical change, from starch. 

 ie) W^hat role does each of the three general classes of foods play in nutrition ? 



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