281. The harmonious mixing of the clay ingredients, is known as
A. weathering
B. blending
C. tempering
D. None of these.

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282. Pick up the correct statement from the following :
A. The average crushing strength of hand moulded bricks is 6000 t/m2
B. The average tensile strength of hand moulded brick is 200 t/m2
C. The average shearing strength of hand moulded brick is 600 t/m2
D. All the above.

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283. The weight of a good quality brick when immersed in water for a period of 16 hours should not exceed the weight of dry brick
A.20%
B.15%
C.10%
D. None of these.

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284. The weight of 1 m3 of brick earth, is about
A. 1200 kg
B. 1500 kg
C. 1800 kg
D. 2000 kg.

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285. The percentage of alumina and silica in good fire clay vary respectively is
A. 25, 75
B. 30, 70
C. 35, 65
D. All of these.

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286. Pick up the correct statement from the following :
A. The percentage of absorption for fire-bricks varies from 5 to 10
B. The percentage of silica in silica bricks is to the extent of about 95 to 97 percent
C. Roughly 1 to 2 percent of lime in silica bricks is added to act as binding material
D. All the above.

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287. Pick up the correct statement from the following:
A. The heating of a material to redness in contact with air, is known as calcinations
B. The property of lime by which it sets or hardens in damp places having no free circulation of ail. is Called setting
C. The product that remains after calcination oflimestone, is called lime
D. All the above.

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