6. Answer (a) and either (b) or (c). 



(a) The valence of cerium (Ce) being four and of indium (In) three, write 

 the formulae of the chlorides, and of the sulphates of each of these ele- 

 ments, and that of the oxide of the latter. 



(b) Why is an aqueous solution of cupric sulphate acid in reaction ? 



(c) Why is silver nitrate in aqueous solution decomposed by the electric 

 current while sugar in solution is not ? 



GROUP C. (Answer all questions in this group.) 



7. (a) How many grams of magnesium would displace all of the hydrogen in 10 



grams of sulphuric acid ? (Atomic weights: Mg, 24; H, i ; S, 32 ; 0, 16.) 

 (b) What is the percentage composition of mercuric oxide ? (Hg, 200.) 



8. (a) What volume of oxygen would be necessary completely to burn, to car- 



bon dioxide and water, ten liters of a gas whose formula is C 3 H 6 ? 

 (b) What volume of carbon dioxide, at normal temperature and pressure, 

 could be formed by the action of an excess of hydrochloric acid upon 100 

 grams of calcium carbonate? (Atomic weights, Ca, 40; C, 12; O, 16; 

 i liter of carbon dioxide at o and 760 m/m. weighs i . 96 g.) 



GROUP D. (Omit one question in this group.) 



9. State the chemical reactions taking place in four of the following processes: 



(a) Action of baking powder; (b) Silver plating; (c) Passing steam over white 

 hot coke; (d) Hardening of plaster of Paris; (e) Manufacture of soap; 

 (f) Manufacture of iron from ferric oxide. 



10. (j) Give the chemical name and formula of one of the most abundant natural 



compounds of each of five of the following elements : (i) socUum, (2) potas- 

 sium, (3) mercury, (4) silicon, (5) phosphorus, (6) sulphur, (7) fluorine. 



(b) Mention one common use of each of five of the following substances, and 

 in each case define the use specifically: (i) silver nitrate, (2) lime, (3) 

 mercuric chloride, (4) alum, (5) carbon dioxide, (6) sulphur, (7) calcium 

 phosphate. 



11. (a) Describe briefly the manufacture of any two of the following substances, 



giving all the important chemical changes: (i) sulphuric acid, (2) sodium 

 carbonate, (3) nitric acid, (4) sodium hydroxide. 



(b) Define and illustrate any two of the following: (i) saturated solution, 

 (2) super-saturated solution, (3) allotropy, (4) catalysis. 



12. (a) Draw a diagram of the Bunsen burner, and state the use of each part. 



(b) Explain spontaneous combustion and illustrate by an example. 



(c) What is acetylene; how is it made; what precautions must be taken in 

 handling it ? 



(d) Write an equation illustrating reduction, and explain how it also illus- 

 trates oxidation. 



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