Fuel and Combustion MCQs

81. The maximum adiabatic flame temperature is attained, when the fuel is burnt with

Theoretically required amount of air

More than theoretically required amount of air

Less than theoretically required amount of air

Theoretically required amount of oxygen

✅ The correct answer is option D.

82. Fixed carbon in coal is defined as

That present in volatile matters

The total quantity of carbon present in the coal

Hundred minus the percentage of volatile matter, ash and moisture

The one which is present in the residue after combustion

✅ The correct answer is option C.

83. Which of the following fuels has the highest calorific value per unit mass (kcal/kg)?

Coal

Kerosene

Natural gas

Furnace oil

✅ The correct answer is option D.

84. Which of the following is called “blue gas”?

Coke oven gas

Water gas

Natural gas

Producer gas

✅ The correct answer is option B.

85. Which of the following has the highest gross calorific value?

Blast furnace gas

Coke oven gas

Carburetted water gas

Oil refinery gas

✅ The correct answer is option D.

86. Which of the following is not used as a binder in coal briquetting?

Tar

Molasses

Pitch

Line

✅ The correct answer is option D.

87. Coking time in a commercial high temperature coal carbonisation plant is about __________ hours.

6

18

28

36

✅ The correct answer is option B.

88. In flue gas analysis by Orsat’s apparatus, carbon monoxide is absorbed by

Cuprous chloride

Potassium hydroxide

Alkaline pyrogallol solution

None of these

✅ The correct answer is option A.

89. Washing of coal decreases its

Caking index

Mineral matter content

Ash content

Both B and C

✅ The correct answer is option B.

90. Hard pitch is used for making

Pulverised fuel

Perfumes

Insecticides

Plastics

✅ The correct answer is option A.