21. Spontaneous combustion of coal on storage results due to
Inadequate ventilation
Low temperature oxidation
Storage in large heaps with small surface to volume ratio
All of the above
✅ The correct answer is option D.
Fuel and Combustion MCQs
22. Benzene is used
As a motor fuel
As an explosive
For making insecticides (e.g., DDT, BHC etc.), detergent & rubber (SBR)
As a perfume
✅ The correct answer is option C.
23. Bright coal
Contains more than 90% durain
Contains more than 90% fussain
Contains mainly vitrain & clarain and is generally coking
Is non-coking
✅ The correct answer is option C.
24. If CO₂ is not fully absorbed by the KOH solution meant for its absorption in the orsat apparatus, it will appear as
O₂
CO
N₂
SO₂
✅ The correct answer is option D.
25. Incomplete combustion of a fuel is characterised by the high __________ in the flue gas.
Smoke
Temperature
Oxygen
Carbon monoxide
✅ The correct answer is option D.
26. In high temperature carbonisation (as compared to low temperature carbonisation) of coal, the
Gas yield is less
Tar yield is more
Ignition temperature of coke produced is less
Aromatic content of tar produced is more
✅ The correct answer is option D.
27. Which of the following has the highest calorific value (kcal/Nm³) ?
Carburetted water gas
Gobar gas
Natural gas
LPG
✅ The correct answer is option D.
28. Which of the following gaseous fuels has the lowest calorific value?
Gobar gas
Refinery gas
Converter gas
Blast furnace gas
✅ The correct answer is option D.
29. Which of the following accounts for maximum energy loss in a boiler?
Flue gases
Ash content in the fuel
Incomplete combustion
Unburnt carbon in flue gases
✅ The correct answer is option A.
30. High ash containing coke
Produces more slag when used in the blast furnace
Has poor strength and abrasion resistance
Is desirable in producer gas manufacture
None of these
✅ The correct answer is option A.