3259. Out of the following fuels, the difference between the net and gross calorific value is maximum in case of
Pitch
Fuel oil
Blast furnace gas
Bituminous coal
✅ The correct answer is option B.
3264. Periclase is
crystalline form of MgO.
MgCO3.
ZrSO4.
amorphous magnesite.
✅ The correct answer is option A.
3273. Which one contains maximum percentage of Al2O3 ?
Firebrick
Sillimanite
Magnesite
Aluminous firebrick
✅ The correct answer is option B.
3278. High porosity refractory bricks have
poor resistance to the peneration of molten slag, metal & flue gases.
poor heat conductivity & low strength.
better thermal spalling resistance.
all (a), (b) and (c).
✅ The correct answer is option D.
3283. Cold crushing strength of ordinary fireclay brick is about 950 kg/cm2 . On exposure to a temperature of about 1500°C, its crushing strength may come down to as low as __________ kg/cm2 .
450
250
150
65
✅ The correct answer is option D.
3288. Main constituents of purified Lurgi gas are
H₂, CmHn & CO₂
CO, H₂ & CH₄
CO₂, O₂ & CO
N₂, H₂ & CO₂
✅ The correct answer is option B.
3293. Ganister is a source of the
silica
periclase
lime
none of these
✅ The correct answer is option A.
3298. Low temperature oxidation of stored coal results in the
Decrease in its caking power & calorific value
Decrease in its carbon & hydrogen content
Increase in its oxygen content
All of the above
✅ The correct answer is option D.
3303. Which of the following is the most poisonous gas?
Coke oven gas
Producer gas
Blast furnace gas
L.converter gas
✅ The correct answer is option D.
3309. Silica refractories
crack when subjected to sudden change of temperature.
can not be used in the dome of hot blast stoves.
have lower thermal conductivity than fireclay bricks.
all (a), (b) and (c)
✅ The correct answer is option A.