337. Asbestos
A. is an excellant insulator for heat and electricity
B. is fire-proof and acid proof
C. has sp. gravity equal to 3.10
D. All the above.

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338. Initial setting time of cement for asbestos cemen products should be not less than
A. 30 minutes
B. 50 minutes
C. 75 minutes
D. 90 minutes.

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339. Asbestos cement
A. is brittle
B. warps due to changes in humidity
C. strength is lowered when saturated by water
D. all the above.

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340. Bitumen completely dissolves in
A. carbon bisulphide
B. chloroform
C. benzol
D. All of these.

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341. For filling cracks in masonry structures, the type of bitumen used, is
A. cut-back bitumen
B. bitumen-emulsion
C. blown bitumen
D. plastic bitumen.

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342.  The main constituent of fly-ash, is
A. aluminium oxide
B. silica
C. ferrous oxide
D. All ofthese.

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343. Inhaling of fly-ash over a long period causes
A. silicosis
B. fibrosis of lungs
C. bronchitis
D. All of these.

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