451. C.V. (kcal/Nm³) of gaseous fuels __________ with increase in molecular weight.
Decreases
Increases
Remains constant
May increase or decrease, depends on combustibles
✅ The correct answer is option D.
Fuel and Combustion MCQs
452. If oxygen content in the flue gas rises too high, fuel is being wasted by
Incomplete combustion
Dry gas/stack gas loss
Moisture loss
None of these
✅ The correct answer is option B.
453. Quantity of coke produced from metallurgical coal may be around __________ percent.
30
50
75
95
✅ The correct answer is option C.
454. Abrasion index of blast furnace coke should be around __________ percent.
20
35
55
80
✅ The correct answer is option D.
455. For maximum discharge through a chimney, its height should be
200 meters
Infinitely long
More than 105.7 metres
Equal to the height of the hot gas column producing draught
✅ The correct answer is option D.
456. Coking time in beehive coke oven is about
12 hours
2-3 days
One week
Two weeks
✅ The correct answer is option B.
457. Supply of excess air for complete combustion of fuel is necessitated to facilitate
Its thorough mixing with air
Attainment of chemical equilibrium
Attainment of high temperature
None of these
✅ The correct answer is option A.
458. Yield of pitch from distillation of high temperature tar is around __________ percent.
10
25
65
90
✅ The correct answer is option C.
459. Rate of low temperature oxidation of coal due to bad storage conditions
Decreases with increase in surface area
Does not vary with increase in surface area
Is more for low volatile coal compared to high volatile coal
Is accelerated by storage in large heaps with small surface to volume ratio
✅ The correct answer is option D.
460. In flue gas analysis by Orsat’s apparatus, carbon dioxide is absorbed by
Potassium hydroxide
Dilute potassium carbonate
Cuporus chloride
Alkaline pyragllol solution
✅ The correct answer is option A.