Free Chemical Process Principles MCQs with Answers
2,710 Chemical Process Principles MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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- 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.
Correct answer: Heat losses- 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.
Correct answer: Risk of explosion- A. Coke oven gas
- B. Natural gas
- C. Water gas
- D. Producer gas
Explanation: Water gas, produced by passing steam over red-hot carbon, mainly contains carbon monoxide and hydrogen and burns with a blue flame.
Correct answer: Water gas- A. Decreases with increase in surface area
- B. Does not vary with increase in surface area
- C. Is more for low volatile coal compared to high volatile coal
- D. Is accelerated by storage in large heaps with small surface to volume ratio
Explanation: Large coal heaps have a small surface-to-volume ratio, so heat generated by slow oxidation is trapped and can accelerate further oxidation…
Correct answer: Is accelerated by storage in large heaps with small surface to volume ratio- A. 15-30
- B. 1-2
- C. 70-100
- D. 150-200
Explanation: Raw blast-furnace gas carries roughly 15 to 30 g of dust per Nm³, mainly fine ore, coke and ash particles.
Correct answer: 15-30- A. Carbonisation
- B. Gasification
- C. Coalification
- D. Oxidation
Explanation: Passing steam over coal to form CO and H₂ is gasification, because solid carbon is converted into a combustible gaseous mixture.
Correct answer: Gasification- A. 0.5
- B. 10
- C. 50
- D. 500
Explanation: Flue-gas velocity in a large power-plant chimney is of the order of 10 m/s.
Correct answer: 10- A. Both B. and C.
- B. Solid
- C. Liquid
- D. Gaseous
Explanation: A bomb calorimeter measures the gross calorific value of solid and liquid fuels by burning a weighed sample in a sealed oxygen vessel.
Correct answer: Both B. and C.- A. Electricity
- B. Both B. & C.
- C. Mixed gas
- D. Coke oven gas
Explanation: Coke ovens are commonly fired with coke-oven gas or a mixed gas, often combining coke-oven and blast-furnace gases.
Correct answer: Both B. & C.- A. Produced by low temperature carbonisation of coal
- B. A domestic fuel
- C. Used in blast furnaces
- D. None of these
Explanation: Soft coke is made by low-temperature carbonisation and is used mainly as a domestic fuel, but it is unsuitable for blast furnaces because…
Correct answer: Used in blast furnaces- A. 10
- B. 25
- C. 45
- D. 60
Explanation: Hydrogen commonly forms about 50 to 60% of coke-oven gas, so 60% is the nearest value.
Correct answer: 60- A. L.D. converter gas
- B. Producer gas
- C. Blast furnace gas
- D. Coke oven gas
Explanation: L.D. converter gas is especially poisonous because it contains a very high concentration of carbon monoxide, which combines strongly with…
Correct answer: L.D. converter gas- A. Higher than
- B. Lower than
- C. Same as
- D. Either A. or B.; depends on the type of coal
Explanation: Gross heating value includes the heat recovered when water vapour in the combustion products condenses, whereas net heating value excludes…
Correct answer: Higher than- A. Reduces its consumption in the furnace
- B. Increases its consumption in the furnace
- C. Does not affect its consumption in the furnace
- D. Decreases its hardness and abrasion resistance
Explanation: Ash is an inert, noncombustible part of coke, so more ash means less effective carbon per unit mass.
Correct answer: Increases its consumption in the furnace- A. Lignite
- B. Bituminous coal
- C. Anthracite
- D. High temperature coke (V.M < 0.5%)
Explanation: The difference between total carbon and fixed carbon is smallest when volatile matter and other non-fixed carbon constituents are minimal.
Correct answer: High temperature coke (V.M < 0.5%)- A. All A., B. and C.
- B. Tar yield is less but free carbon in tar is more
- C. Calorific value of coke oven gas is less
- D. Coke oven gas yield is more
Explanation: High-temperature carbonisation produces more coke-oven gas, while the tar yield falls and its free-carbon content rises.
Correct answer: All A., B. and C.- A. More
- B. Less
- C. Equal
- D. More or less; (depends on the state of fuel.)
Explanation: For combustion under the usual comparison conditions, chemical energy is released, leaving the products at a lower internal-energy level…
Correct answer: Less- A. A high rank coal
- B. A coking coal
- C. Can be used for gasification and steam generation
- D. A black banded coal which burns with a non-smoky yellowish flame
Explanation: Lignite is a low-rank coal with high moisture and relatively low carbon content, so it is not normally a high-rank or strong coking coal.
Correct answer: Can be used for gasification and steam generation- A. None of these
- B. Kopper-Totzek
- C. Winkler
- D. Lurgi
Explanation: The Lurgi process is a pressurised fixed-bed coal-gasification process.
Correct answer: Lurgi- A. Better combustion
- B. High calorific value
- C. Smokeless burning
- D. Less erosion on furnace walls
Explanation: Pulverising coal greatly increases its surface area, allowing rapid mixing with air and more complete combustion in the furnace.
Correct answer: Better combustion