Fuels and Combustion MCQs

Question 1

Froth floatation is used for

Accepted Answer

Washing fine coal dust (< 0.5 mm size)

Answer

Washing lump coal (> 80 mm size)

Answer

Removing ash from the coal based on difference in specific gravity of coal and ash

Answer

All of the above

Question 2

Main use of soft coke is as __________ fuel.

Accepted Answer

Domestic

Answer

Blastfurnace

Answer

Foundary

Answer

None of these

Question 3

Fussain . . . . . . . .

Accepted Answer

All of the above

Answer

Is friable, charcoal like substance

Answer

Has highest fixed carbon and lowest volatile matter content of all the four banded components of coal

Answer

Is non-coking, but when blended with highly coking coal, controls its swelling and produces high strength coke on carbonisation

Question 4

Deficiency of combustion air during combustion of a gaseous fuel

Accepted Answer

Both A & B

Answer

Lengthens the flame

Answer

Causes heat loss of fuel by its partial combustion

Answer

Shortens the flame

Question 5

Which of the following is not a manufactured fuel ?

Accepted Answer

Bagasse

Answer

Furnace oil

Answer

Semi-coke

Answer

Kerosene

Question 6

Preheating of combustion air is done to

Accepted Answer

Increase the adiabatic flame temperature

Answer

Increase the calorific value of the fuel

Answer

Complete the combustion of fuel

Answer

Reduce its requirement for effecting the complete combustion

Question 7

Theoretical flame temperature of a fuel is that temperature which is attained, when the fuel is completely burnt 'using theoretical amount of air in

Accepted Answer

Either A or C without gain or loss of heat

Answer

Air

Answer

Oxygen

Answer

Either A or B

Question 8

With increase in the time of carbonisation at a particular temperature (say 1000°C), the __________ percentage in coke oven gas increases.

Accepted Answer

Hydrogen

Answer

Methane

Answer

Unsaturated hydrocarbons

Answer

All of the above

Question 9

Assam coals suffers mainly from the disadvantage of high __________ content.

Accepted Answer

Sulphur (4-6%)

Answer

Ash

Answer

Volatile matter

Answer

Moisture