1 18 CHEMISTR V FOR A GRICULTURAL STUDENTS 



14. Under what conditions (if any) can copper, mercury, silver, gold, and 



platinum be oxidised? What experiment can you cite to show 

 that heated copper has no action on steam? 



15. Distribute the metals barium, calcium, copper, gold, iron, 



magnesium, mercury, potassium, sodium, strontium, and zinc, into 

 five groups, and ascribe a name to each group. 



16. What is meant by the terms "alkali" and "alkaline earth"? 



Why are gold and silver described as noble metals ? 



17. Give two or three instances of the grouping of metals holding good 



not only for oxidisability, but also for the solubility of the oxides, 

 and for the specific gravity, fusibility, malleability and ductility, 

 or conductivity of the metals. 



18. Give an instance of metals of the same group occurring together in 



nature. What metals are found in the free state in nature ? 



What are the minerals loadstone, haematite, emery, tinstone, and 



pyrolusite ? 

 *I9. To what group should the metal be ascribed, as judged by its 



oxidisability? (Tin.) 

 *20. Identify the metal in the salt by the colour of its incandescent vapour. 



(Sodium, potassium, calcium, strontium, or barium.) 

 •^21, Is the metallic oxide an "alkali," an "alkaline earth," or an 



"earth"? (Soda, potash, lime, baryta, magnesia, or oxide of 



zinc.) 



The Metals: their Physical Properties. 



22. What is an alloy ? Is the property of forming alloys possessed by all 



the elements ? Why are gold and silver alloyed with copper for 

 purposes of coinage ? Why are tin and lead alloyed for use as 

 solder ? 



23. What do you understand by the malleability and ductility of metals? 



Name the most malleable and one of the most ductile of metals. 



24. Are metals as a rule good or bad conductors of heat and electricity ? 



Name two of the best conductors. 



25. Give an instance of the expansion of metals by heat and its effect 



upon any structure or instrument. 



26. Why should a mercurial thermometer be so sensitive to rapid changes 



of temperature ? 



27. Name a metal whose density is less than that of water, and a metal 



whose density is greater than mercury. 



28. Name metals which are (i) liquid at the ordinary temperature, (2) 



fusible below 100°, (3) fusible below a red heat, (4) fusible at a red 

 heat, and (5) only fusible at a white heat. If one metal be alloyed 



