All Free Chemical Engineering MCQs with Answers

• A. Air
• B. Nitrogen
• C. Phenolic water
• D. Carbon dioxide

Explanation: Dry coke quenching uses an inert gas, normally nitrogen, to remove heat without burning the hot coke.

• A. Moisture, ash, sulphur & volatile matter
• B. Moisture, sulphur, nitrogen & fixed carbon
• C. Moisture, volatile matter, ash & fixed carbon
• D. None of these

Explanation: Proximate analysis divides coal into moisture, volatile matter, ash and fixed carbon.

• A. 21
• B. 77
• C. 79
• D. 29

Explanation: For combustion with air, the nitrogen accompanying the oxygen remains in the flue gas, limiting the theoretical dry CO₂ concentration to…

• A. 10
• B. 25
• C. 65
• D. 90

Explanation: High-temperature coal tar contains a large heavy fraction, and its pitch yield is commonly around 65%.

• A. 50
• B. 70
• C. 85
• D. 100

Explanation: The Hardgrove Grindability Index increases as coal becomes easier to pulverise.

• A. 3 & 10
• B. 10 & 20
• C. 10 & 3
• D. 15 & 8

Explanation: Low-temperature carbonisation produces more tar, commonly about 10%, whereas high-temperature carbonisation gives about 3% tar because…

• A. Low calorific value
• B. Non smoking tendency
• C. Low ash content
• D. High volatile matter

Explanation: Fat coal is a bituminous coal rich in volatile matter and strongly caking, so it gives a smoky flame on burning.

• A. 100
• B. 0
• C. In between 0 and 100
• D. More than 100

Explanation: 2,2,4-Trimethylpentane is iso-octane, the reference fuel assigned an octane number of 100. The zero reference is n-heptane.

• A. Lignite
• B. Sub-bituminous coal
• C. Anthracite
• D. Peat

Explanation: Anthracite is the highest-rank coal, with the greatest fixed-carbon content and generally the highest calorific value.

• A. CO
• B. CO2
• C. H2O
• D. Both B. & C.

Explanation: Complete combustion of acetylene converts its carbon to CO2 and its hydrogen to H2O.

• A. 25-30
• B. 3-5
• C. 60-65
• D. 95-100

Explanation: A bomb calorimeter is charged with oxygen at roughly 25 to 30 atm so the sample burns completely in a sealed vessel.

• A. 1800
• B. 800
• C. 4500
• D. 10000

Explanation: LD converter gas is rich in carbon monoxide and has a calorific value of approximately 1,800 kcal/Nm3.

• A. Specific gravity
• B. Octane number
• C. Calorific value
• D. Viscosity

Explanation: Alcohol contains oxygen in its molecule and releases less heat per kilogram than hydrocarbon gasoline, so its calorific value is lower.

• A. Vitrain
• B. Clarain
• C. Durain
• D. Fussain

Explanation: Fusain is a porous, brittle, charcoal-like coal constituent that is non-caking and therefore non-coking.

• A. Neumann reversal
• B. Boudouard
• C. Shift conversion
• D. Reduction

Explanation: The reaction C + CO₂ ⇌ 2CO is the Boudouard reaction, an endothermic reduction of carbon dioxide by carbon.

• A. Is not undesirable
• B. Reduces its calorific value
• C. Badly affects the quality of steel
• D. Increases its caking power

Explanation: Phosphorus from metallurgical coal can enter the molten iron and makes steel brittle, especially at lower temperatures.

• A. Carburetted water gas
• B. Coke oven gas
• C. Water gas
• D. Blast furnace gas

Explanation: Blast furnace gas contains a large proportion of carbon dioxide and nitrogen, giving it the highest average molecular weight and density…

• A. 1300
• B. 500
• C. 4500
• D. 9000

Explanation: Producer gas is mainly carbon monoxide, hydrogen, nitrogen and carbon dioxide, with nitrogen diluting its combustibles.

• A. High amount/current of combustion air
• B. Low amount/current of combustion air
• C. Preheated secondary air
• D. Very little excess air

Explanation: A high rate or velocity of combustion air promotes rapid turbulent mixing with the gas, producing a short, intense flame.

• A. Use of thick fire bed
• B. All A., B. & C.
• C. Use of preheated primary air
• D. Low fusion point of ash (< 1100° C)

Explanation: A thick fire bed, low ash-fusion temperature and preheated primary air all raise local bed temperature or increase the amount of ash that…