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14. Name or describe one useful property of each of the following substances, 



and give one use made of it because of this property : blaked lime, distilled 

 water, charcoal, sulphur dioxide, aluminium, sodium nitrate, cast iron, 

 copper sulphate, coke, lead. 



15. a) How can decomposed organic matter be removed from water without J^ 



distillation ? 



b) How can bacteria in drinking-water be destroyed without raising its 



temperature ? 



c) How can temporary hardness in water be removed without raising its 



temperature ? 



d) How can water be freed from dissolved ammonia ? 



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