All Free Chemical Engineering MCQs with Answers

• A. None of these
• B. Bituminous coal
• C. Anthracite coal
• D. Lignite

Explanation: Lignite has sufficient inherent binding and plastic properties to form briquettes without adding a separate binder.

• A. 80-170
• B. 200-300
• C. 250-270
• D. 280-300

Explanation: Light oil is the low-boiling crude-tar fraction, typically collected at about 80 to 170°C, and contains benzene or benzol as a major…

• A. Coke oven gas and L.P.G
• B. Coke oven gas and converter gas
• C. B.F. gas and coke oven gas
• D. Blast furnace gas and naphtha vapor

Explanation: Mixed gas in an integrated steel plant commonly combines low-calorific blast-furnace gas with higher-calorific coke-oven gas.

• A. Reduce its requirement for effecting the complete combustion
• B. Increase the calorific value of the fuel
• C. Complete the combustion of fuel
• D. Increase the adiabatic flame temperature

Explanation: Preheating combustion air supplies part of the sensible heat before combustion begins, raising the adiabatic flame temperature.

• A. 350 to 450
• B. 100 to 150
• C. 550 to 650
• D. 700 to 850

Explanation: Coal softens and forms a plastic layer during carbonisation at approximately 350 to 450°C.

• A. Ash
• B. Inherent mineral matter
• C. Free impurities
• D. Volatile matter

Explanation: Inherent mineral matter is finely distributed within the coal particles, so ordinary washing cannot separate it effectively.

• A. Produce smaller coke
• B. Produce stronger coke
• C. All A., B. and C.
• D. Require less time of carbonisation

Explanation: Narrow coke ovens provide a shorter distance for heat to penetrate, allowing faster carbonisation and generally producing smaller…

• A. Neptunium
• B. Uranium
• C. Radium
• D. Plutonium

Explanation: Plutonium-239 is the usual fuel for a fast breeder reactor, while uranium-238 is commonly placed in the blanket to breed more plutonium.

• A. Decreases
• B. May increase or decrease, depends on combustibles
• C. Remain constant
• D. Increases

Explanation: Calorific value per normal cubic metre depends on the combustible gases present, not on molecular weight alone.

• A. 22-26
• B. 10-15
• C. 1-2
• D. 30-33

Explanation: Metallurgical coke is strongly devolatilised during coking, so its volatile matter is typically only about 1 to 2 percent.

• A. Lignites
• B. Anthracites
• C. Semi-anthracites
• D. Bituminous coals

Explanation: Coking properties are chiefly associated with bituminous coals, which soften and form a coherent porous coke on heating.

• A. Ratio of fixed carbon to volatile matter increases
• B. High rank coals have higher amount of volatile matter
• C. Oxygen content progressively decreases
• D. Calorific value of the coal increases

Explanation: As coal rank increases, volatile matter decreases while fixed carbon becomes a larger fraction of the coal.

• A. 2
• B. 4
• C. 6
• D. 1

Explanation: The combustion equation is CH₄ + 2O₂ → CO₂ + 2H₂O, so one volume of methane requires two volumes of oxygen at the same conditions.

• A. Either lower or higher, depends on the type of fuel
• B. Much higher
• C. Same
• D. Much lower

Explanation: Air contains a large amount of nitrogen that absorbs heat without supporting combustion, so the adiabatic flame temperature is much lower…

• A. 1
• B. 5
• C. 50
• D. 100

Explanation: Raw coke-oven gas typically contains ammonia at roughly 5 g/Nm³, formed from the nitrogen compounds in coal during carbonisation.

• A. Oxygen
• B. Sulphur
• C. Hydrogen
• D. Carbon

Explanation: Oxygen is already in an oxidised state and releases no useful heat by further combustion, so it contributes nothing to the fuel's…

• A. CO
• B. H2
• C. CH4
• D. C2H6

Explanation: Hydrogen has the highest flame speed among the listed fuels because its small, highly diffusive molecules mix and react very rapidly with…

• A. Furnace oil, light diesel oil and tar/PCM
• B. Coal middling from washeries
• C. Pulverised coking coal
• D. B.F. gas, coke oven gas and L.D. converter gas

Explanation: Pulverised coking coal is primarily reserved for metallurgical coke production, whereas thermal boilers generally fire non-coking coal or…

• A. None of these
• B. Long flame
• C. Condensation of water vapour from the fuel gas
• D. Heat losses

Explanation: Excess air carries additional nitrogen and unused oxygen out with the flue gas, increasing sensible heat loss through the stack.

• A. Requirement of large volume combustion chamber
• B. Risk of explosion
• C. Chances of clinker formation
• D. Incomplete combustion of coal

Explanation: Pulverised coal forms a combustible dust-air mixture, and excessive preheating can ignite this mixture inside the conveying system.