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By which of the following processes is an oxide ore readuced to the free metal ?A. CalcinationB. LeachingC. SmeltingD. Roasting |
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Answer» Correct Answer - c The process of extracting the metal by heating the metal oxide with a suitable reducing agent is called smehing it is one of the steps involved in protonetallergy .The method used for depends on how strongly the metal ions are bonded to unitens .When the holding is string more energy is ewquired to reduces the metal.This metals reduction more exprensive to reduced the most active metals usually have the string holding . The most reactive metals `(Au, A,Pt,etc)` occure in the free state and thus requite no reduction.This is why prehistoric times. Some less active jmetals such as `Hg` .can be obtained directly from their sulphides ores by readuced metal inos to th efree metals by oxidetion of the sulphide ions `underset("Cinnabar")(HgS (s)) + underset("from air")(O_(2)(g)) overset(Delta)(to) SO_(2)(g) + underset({:("obtained as vapour"),("later condensed"):})(Hg(g))` Roasting sulphides of the more active metals produces metal oxides , but no free metals `2NS(s) + 3O_(2)(g) overset(Delta) To 2NiO(s) + 2SO_(2)(g)` The resulting metals oxide are then reducing to free metals with coke or `CO`if `C` most be arosided, amother roducting agent , such as `H_(2),F_(2) , or Al` is used `SaO_(2)(s) + 2C(s) overset (Delta) To Sa(1) + 2CO_(g)` `WO_(3)(s) + 3H_(2)(g) overset(Delta) To W(s) + 2H_(2)O(g)` THe very active metaqls such as `Al` and ` Na` are reduced electrochemically usually from their anlydrous moleten salts if `H_(2)O` is present , it is reduced of the more active metals |
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