13. Principles of Metallurgy

1. ____________ the process of extraction of metals from their ores.

2. Bronze is an alloy of ____________.

3. The elements or compounds of the metals which occur in nature in the earth crust are called _________.

4. The minerals from which the metals are extracted without economical loss are called _________.

5. 50–70 % of aluminiumoxide is extracted from ___________.

6. You will notice that the ores of many metals are ________ and sulphides.

7. The impurities like clay in a ore is called _________.

8. __________ method is mainly useful for sulphide ores which have no wetting property whereas the impurities getwetted.

9. If the ore or impurity, one of them is magnetic substance and the other non-magnetic substance they are separated using ___________.

10. Arrangement of the metals in decreasing order of their reactivity is known as ____________.

11. Sulphide ores are converted into oxides by heating them strongly in excess of air. This process is known as ___________.

12. __________ process involves the reaction of metal oxides with aluminium.

13. Sodium, calcium, aluminium etc. are highly reactive metals and are used as _____________.

14. The reaction of Iron oxide (Fe2O3), with aluminium is used to join railings of railway tracks or cracked machine parts. This reaction is known as the _____________.

15. The chemical formula of cinnabar is ______.

16. When cinnabar (HgS) which is an ore of ________.

17. The process of obtaining the pure metal from the impure metal is called _______ of the metal.

18. ____________ method is very useful for purification of low boiling metals like zinc and mercury containing high boiling metals as impurities.

19. The extracted metal in the molten state is distilled to obtain the pure metal as ___________.

20. Blister copper is purified by ____________.