GROUP C. (Omit one question.) 

 (Put all your work upon the paper.) 



8. (a) Calculate the percentage of chlorine in hydrated barium chloride (BaCL 3 , 



2 H 2 O). (Ba = i 3 7, = 35.5, H = i, O=i6.) 



(b) How many grams of sulphuric acid (H 2 SO 4 ) reacting with an excess of 

 sodium carbonate (Na 2 CO 3 ) are required to produce 200 g. of carbon 

 dioxide (CO 2 ) ? (H=i, 8 = 32, O=i6, Na = 23, = 12). 



(c) How many volumes of oxygen are required to burn one volume of 

 methane to carbon dioxide and water ? 



9. (a) What weight of carbon dioxide is required to precipitate completely the 



calcium in i g. calcium hydroxide? (C = i2, Ca = 4o, O=i6, H = i.) 



(b) What volume will this weight of carbon dioxide occupy at room tempera- 

 ture and 760 mm. ? (One liter of CO 2 , at room temperature and 760 mm. 

 weighs i.gg.) 



(c) Assuming that each bubble of carbon dioxide contains o . 3 c.c., how many 

 bubbles will be required; and assuming that they pass at the rate of 

 5 per second, how long will the operation take ? 



(d) Two grams of a substance lose water upon heating, and the residue 

 weighs i . 72 g.: what per cent of water was lost ? 



GROUP D. (Omit one question.) 



10. (a) Give the reasons for any three of the following facts: 



(1) A solution of chlorine water bleaches writing ink but does not bleach 

 printer's ink; 



(2) iron rusts very rapidly at the sea-shore; 



(3) sodium carbonate is used in washing-powders; 



(4) lemon juice is used to remove iron rust from cloth; 



(5) graphite is used in stove polishes; 



(6) calcium carbonate is used in tooth powders. 



(b) Answer three of the following: Describe the structure and operation of 

 the (i) blast lamp, (2) calcium light, (3) Welsbach light. Give the 

 composition of (4) galvanized iron, (5) baking powder. Describe the 

 process of (6) copper-plating. 



11. (a) Give the formula, chemical name, color, and one use of any four of the 



following: coke, Epsom salt, calomel, alum, laughing gas, phosphoric 

 anhydride, corundum, silica. 

 (b) (i) What is the natural source of sodium compounds? 



(2) How is metallic sodium prepared ? 



(3) How can the presence of sodium in a compound be shown ? 



(4) Give the formulae and uses of three compounds of sodium. 



12. (a) Describe briefly one typical method used in obtaining metals from their 



ores. 



(b) Name two physical properties of metals which serve to distinguish them 

 from substances which are not metals. 



(c) Write an equation to illustrate one characteristic property of the 

 hydroxides of the metals. 



(d) Name two metals which displace free hydrogen from dilute acids, and 

 two which do not. 



