Page 2 



Part II 



{Omit one group. Each question counts 10.) 



Group A 



C. (a) Classify as oxidizing or reducing agents the following substances: hot 

 concentrated H,S04, H.S, HOCl, H^SO^, concentrated HNO3. 

 ib) Make three pairs by combinations of the above which will react with each 

 other to form new substances. 



7. (c) Outline briefly a laboratory method for obtaining a pure sample of 



(1) sulphur crystals from powdered sulphur, (2) ferric hydroxide from 

 iron. 

 {h) Name two substances which in reacting upon each other can yield (1) an 

 element by reduction of a compound of that element, (2) an element 

 by oxidation of a compound of that element, (3) a soluble salt by direct 

 combination, (4) an insoluble sulphide by precipitation. 



Group B 



8. Considering each of the following statements separately, explain why you 



consider it to be an experimental fact or an assumption: (a) The composi- 

 tion of a given compound does not vary. (6) Two atoms of iron have the 

 same weight, (c) The materials composing foods cannot be put out of 

 existence, {d) Some compounds ionize when dissolved in water, (e) Five 

 grams of hydrogen may be found united with forty grams of oxygen or 

 with eighty grams. Name the theory or law which apphes in each case. 



9. A dirigible balloon at sea-level contains 400,000 cubic feet of gas measured 



at a pressure of 774 mm. of mercury and at a temperature of 27° C. It 

 rises to an elevation at which the pressure is reduced to 430 mm. and the 

 temperature to —23° C. What is the volume of the gas under the latter 

 conditions, assuming that none is allowed to escape from the containers ? 



Group C 



10. (c) What component do rice, tapioca, and potatoes have in common ? How 



could this component be identified ? 

 (6) What are the products of the fermentation of glucose? Why do the 



bubbles of gas not appear at once in this fermentation ? 

 (c) Describe the preparation of water gas and write an equation for the 



reaction involved. 



11. How could it be determined by chemical means if a sample of (a) water were 



hard or soft? {h) hard water had temporary- or permanent hardness? 

 (c) washing powder contained sodium carbonate ? id) metal was gold or 

 ^rass? (e) beverage contained alcohol? 



