Building Materials

11. Assertion A : Pure lime takes a long time to develop adequate strength. Reason R : Pure lime has slow hardening characteristics. Select your answer according to the coding system given below:

1. Both A and R is true and R is correct explanation of A
2. Both A and R is true and R is not a correct explanation of A
3. A is true but R is false
4. A is false but R is true

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12. Bitumen may be dissolved in

1. Carbondioxide
2. Water
3. Sodium chloride
4. Carbon disulphide

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13. Blister steel

1. Is obtained by cementation process
2. Is full of fissures and cavities
3. Can be easily welded
4. All the above

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14. Bullet proof glass is made of thick glass sheet sandwiched by a layer of

1. Steel
2. Stainless steel
3. Can be easily welded
4. Chromium plate

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15. Cast iron

1. Is obtained by purifying pig iron
2. Is manufactured in required shapes
3. May contain 2 to 5 per cent of carbon with other impurities
4. All the above

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16. Cast iron contains carbon approximately

1. 1.5% to 5.5%
2. 0.05% to 1.75%
3. 0.250%
4. None to these

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17. Chlorite, a green colour mineral is mainly derived from the decomposition of

1. Augite
2. Biotite
3. Hornblende
4. All of these

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18. Clay and silt content in a good brick earth must be at least

1. 50%
2. 40%
3. 30%
4. 25%

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19. Compared to mild steel, cast iron has
(i) High compressive strength
(ii) High tensile strength
(iii) Low compressive strength
(iv) Low tensile strength
The correct answer is

1. (i) and (ii)
2. (ii) and (iii)
3. (iii) and (iv)
4. (i) and (iv)

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20. During pudding

1. Molten metal is kept clear of the fuel
2. Carbon is converted into carbonic acid gas
3. Silicon forms a slag
4. All the above

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