51.
Which one of the following mineral does not contain oxygen ?

52.
Which mineral is the ore of aluminium ?

53.
Which of the following is a metallic ore ?

54.
Magnalium is an alloy of

55.
Magnetite is

57.
Food cans are coated with tin and not with zinc because

58.
Cinnabar is an ore/mineral of

59.
The percentage of carbon in cast iron is :

60.
Brass is a solution of molten copper in