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1. What is the significance of leaching in theextraction of aluminium?
2. Is it true that under certain conditions, Mg can reduceSiO2 and Si can reduce MgO? What are those conditions?
3. Copper can be extracted by hydrometallurgy but notzinc. Explain.
4. What is meant by (a) Depressant (b) Froth stabilizer ?
5. Why is the extraction of copper from pyrites moredifficult than that from its oxide ore through reduction?
6. Explain: (i) Zone refining (ii) Columnchromatography.
7.Out of C and CO, which is a betterreducing agent at 673 K?
8. Write down the reactions taking place in differentzones in the blast furnace during the extraction of iron. 
9. State the role of silica in the metallurgy of copper.
10. How can you separate alumina from silica in bauxiteore associated with silica?
11. Giving examples, differentiatebetween ‘roasting’ and ‘calcination’.
12. How is ‘cast iron’ different from‘pig iron”?
13. Why copper matte is put in silica linedconverter?
14. What is the role of cryolite in the metallurgy ofaluminium?
15. Out of C and CO, which is a better reducing agent forZnO ?
16. Name the processes from which chlorine is obtained asa by-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?
17. What is the role of graphite rodin the electrometallurgy of aluminium?
18. Outline the principles of refining of metals by thefollowing methods:
(i)Zonerefining (ii) Electrolyticrefining (iii) Vapour phaserefining