question_answer

(a) In column I different methods of extraction are given. Name the methods used for the extraction of metals given in Column II:
Column - I	Column - II
(i) Reduction with carbon	Al, Zn, Na, Fe, Mn, Pb
(ii) Electrolytic reduction
(iii) Reduction with aluminium
(b) Differentiate between roasting and calcination processes giving one example of each.

 

Answer:

           

(a)
Column ? I	Column ? II
(i) Reduction with carbon	Zn, Fe, Pb
(ii) Electrolytic reduction	Al, Na
(iii) Reduction with aluminium	Mn
(b) Difference between roasting and calcination.
Roasting	Calcination
1. Roasting is done in case of sulphide ores.	Calcination is done in case of carbonate ores.
2. In this, the ore is heated in the presence of excess air to convert it into its oxide compound.	The carbonate ore is heated in the absence of air (limited supply of air) to convert into its oxide.
3. The gas given out is \[S{{O}_{2}}\] (sulphur dioxide) gas.	The gas given out is \[C{{O}_{2}}\] (carbon dioxide) gas.
4. Example: \[2ZnS+\underset{(Air)}{\mathop{3{{O}_{2}}}}\,\xrightarrow{Heat}2ZnO+2S{{O}_{2}}\uparrow \]	Example: \[ZnC{{O}_{3}}\xrightarrow{Heat}ZnO+C{{O}_{2}}_{{}}\uparrow \]