71. Hardness of upper bainite (acicular structure) is about
A.RC 65
B.RC 48
C.RC 57
D.RC 80
72. Carbon in iron is an example of
A.Substitutional solution
B.Interstitial solid solution
C.Intermetallic compounds
D.All of the above
73. Brass (alloy of copper and zinc) is an example of
A.Substitutional solid solution
B.Interstitial solid solution
C.Intermetallic compounds
D.All of the above
74. Which is false statement about annealing. Annealing is done to
A.Relieve stresses
B.Harden steel slightly
C.Improve machining characteristic
D.Soften material
75. Argentite is the principal ore or raw material for
A.Aluminium
B.Silver
C.Zinc
D.Lead
76. Hardness of lower bainite (tempered martensite) is about
A.RC 65
B.RC 48
C.RC 57
D.RC 80
77. Sphalerite is the principal ore or raw material for
A.Zinc
B.Silver
C.Tin
D.Magnesium
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