21. In an electrolytic refining method, the __________ is made to act as anode.
22. In ________________, a metal is oxidized by loss of electrons generally to oxygen and results in the formation of oxides.
23. Corrosion of iron (commonly known as rusting) occurs in presence of _________ and _______ .
24. To prevent corrosion of metals by covering the surface with paint or by some chemicals like ____________.
25. ___________ is a method of improving the properties of a metal.
26. When iron is mixed with nickel and chromium we get ____________ which will not rust.
27. Pure gold is not suitable for making ___________.
28. __________ is a pyrochemical (pyre = heat) process, in which the ore is mixed with flux and fuel and strongly heated.
29. During _________ the impurities (gangue) in the ore react with flux to form slag which is removed.
30. Roasting is a ______________ in which the ore is heated in the presence of oxygen or air below its melting point.
31. ___________ are a pyrochemical process in which the ore is heated in the absence of air.
32. ___________ is a substance added to the ore to remove the gangue from it by reacting with the gangue.
33. Furnace is the one which is used to carry out ___________ in metallurgy.
34. __________ is the outlet through which flue (waste) gases go out of the furnace.
35. A metallic compound occurring in the earth crust along with impurities is called __________.
36. A mineral from which a metal can be extracted economically and conveniently is called _______.
37. The impurity present in the ore is called _________.
38. The substance added to the ore to remove gangue from it is called _______.
39. ____________ are a process of heating the ore strongly in the absence of air or oxygen.
40. During calcinations, carbonate is converted to its ________.
41. ____________ is a process of heating the ore strongly in a free supply of air or oxygen.
42. Calcinations and Roasting are carried out in a ______________ .
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