Refractory Technology

181. Which is a neutral refractory?

1. Graphite
2. Magnesite chrome
3. Silica
4. Magnesia

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182. Which is an acidic refractory?

1. Magnesite
2. Dolomite
3. Fireclay
4. Chrome magnesite

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183. Which is not a basic refractory?

1. Chrome magnesite
2. Magnesite
3. Dolomite
4. Silicon carbide

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184. Which is not a high alumina refractory?

1. Mullite
2. Corundum
3. Bauxite
4. Dolomite

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185. Which is not a natural insulating material?

1. Diatomaceous earth/kieselgur
2. Asbestos
3. Vermiculite
4. None of these

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186. Which is not an acidic refractory?

1. Silica
2. Fireclay
3. High alumina refractory
4. Carbon black

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187. Which is not an alumino-silicate refractory?

1. Fireclay bricks
2. Mullite bricks
3. Tar dolomite bricks
4. High alumina bricks

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188. Which is required in an insulating refractory?

1. High thermal conductivity
2. Low porosity
3. Both (A) and (B)
4. Neither (A) nor (B)

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189. Which is the most stable crystalline form of silica at room temperature?

1. Quartz
2. Cristobalite
3. Tridymite
4. None of these

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190. Which is the stable form of silica below 870°C?

1. Tridymite
2. Cristobalite
3. Quartz
4. None of these

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