Stoichiometry

261. Refractories used in/for _________ should have low thermal conductivity.

1. Coke ovens
2. Insulation
3. Regenerators
4. Muffle furnaces

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262. Refractoriness/fusion points of 'Superduty' refractories is _________ °C.

1. 1520-1630
2. 1630-1670
3. > 1730
4. > 2000

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263. Refractory bricks having lower porosity have

1. High insulating properties
2. Low heat capacity
3. Low thermal conductivity
4. Greater strength

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264. Refractory bricks with lower permeability is produced by using

1. Higher firing temperature
2. Higher moulding pressure
3. Finer grog size
4. All (A), (B) and (C)

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265. Roof of a basic electric furnace is made of _________ bricks.

1. Superduty fireclay
2. Silica
3. Chromite
4. None of these

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266. S.T.P. corresponds to

1. 1 atm. absolute pressure & 15.5°C
2. 760 mm Hg gauge pressure & 15.5°C
3. 760 torr & 0°C
4. 101.325 kPa gauge pressure & 15.5°C

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267. Saturated molal absolute humidity of the vapor-gas mixture depends upon the

1. Vapor pressure at dry bulb temperature
2. Total pressure
3. Both (A) and (B)
4. Neither (A) nor (B)

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268. Saturated solution of benzene in water is in equilibrium with a mixture of air and vapours of benzene and water at room temperature and pressure. Mole fraction of benzene in liquid is x_B and the vapour pressures of benzene and water at these conditions are pv ^B and pv ^w respectively. The partial pressure of benzene in air-vapour mixture is

1. P_v^B
2. x_B.P_v^B
3. (P_atm - P_v^w)x_B
4. x_B.P_atm

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269. Silica bricks are never used for lining the

1. Beehive coke ovens
2. By-product coke ovens
3. Dome of blast furnace stoves
4. Roof of open hearth furnace

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270. Simultaneous doubling of the absolute temperature of a gas and reduction of its pressure to half will result in _________ in the volume of the gas.

1. No change
2. Doubling
3. 1/4th reduction
4. Fourfold increase

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