Civil Engineering - Building Materials

41. 

The slag which floats on the surface of the molten iron generally contains

A. Lime (CaO) 45%
B. Silica (SiO2) 35%
C. Alumina (Al2O3) 12%
D. MgO, CaSO4, KMnO2 and FeO 8%
E. all the above.

Answer: Option E

Explanation:

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42. 

Minimum of 40% of iron, is available in

A. Magnetite
B. Red haemetite
C. Limonite
D. Siderite
E. Black band.

Answer: Option E

Explanation:

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43. 

If the iron ore contains clay as an impurity, the flux added during calcination, is

A. clay
B. lime stone
C. argillaceous iron ore
D. all the above.

Answer: Option B

Explanation:

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44. 

Cement is said to be of good quality if

A. its colour is not greenish grey
B. one feels cool by thrusting one's hand in the cement bag
C. it is not smooth when rubbed in between fingers
D. a handful of cement thrown into a bucket of water does not float
E. none of these.

Answer: Option E

Explanation:

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45. 

Cast steel is manufactured by

A. Cementation process
B. Crucible process
C. Bessemer process
D. Open hearth process.

Answer: Option B

Explanation:

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