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 ______________ .