260. The wedging is adopted for quarrying costly stratified rock such as
A. laterite
B. marble
C. limestone
D. All the above.

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261. The stones obtained by blasting are used as
A. ballast in railways
B. aggregates for concrete
C. roadmetal
D. All the above.

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262. The proportions of charcoal, saltpetre and sulphur in gun powder by weight, are respectively :
A. 15, 75, 10
B. 75,10, 15
C. 10, 15, 75
D. 10,75,15

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263. For sanitary pipes and chemical stonewares,
A. salt glazing is used
B. lead glazing is used
C. opaque glazing is used
D. None of these.

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264. Quartzite, a metamorphic stone is
A. hard
B. brittle
C. crystalline
D. All the above.

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265. The melting point of silica is :
A. 1570?C
B. 1630?C
C. 1730?C
D. 1850?C.

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266. The silica is used for preparing
A. silica bricks
B. coke oven
C. lining for glass furnaces
D. all of these.

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