51. What is at No.10 in Mohs scale of mineral hardness?
52. What was the main part of the Atanasoff - Berry computer?
53. What is the most common metal found on Earth?
54. What is the melting point of aluminum?
55. What is the most important ore of aluminium?
56. Adding impurities to a pure intrinsic semiconductor is called:
57. The gas usually filled in the electric bulb is:
58. What is the centre of an atom called?
59. Bronze is a mixture of:
Copper and Tin
Nickel and Zinc
Copper and Manganese
Copper and Zinc
60. What is the chemical formula of Ozone?