151. The machinability of steel is increased by
Correct answer: (B)
phosphorous, lead and sulphur
152. The metallic structure of mild steel is
Correct answer: (A)
body centred cubic
153. The molecules in a solid move
Correct answer: (D)
back and forth like tiny pendulums
154. The most effective inhibitor of grain growth, when added in small quantities is
Correct answer: (B)
vanadium
155. The number of electrons in 1 cm3 of metal would be of the order of
Correct answer: (C)
1022
156. The percentage of carbon in grey iron castings usually varies between
Correct answer: (C)
2.5 to 4.5%
157. The percentage of carbon in low carbon steel is
Correct answer: (B)
0.15%
158. The percentage of carbon in pig iron varies from
Correct answer: (D)
4 to 4.5%
159. The presence of sulphur in pig iron makes
Correct answer: (D)
the casting unsound
160. The surface hardness of the following order is achieved by nitriding operation
Correct answer: (C)
1000 to 1100 VPN