Free Chemical Process Principles MCQs with Answers

• A. Combustion of fuel is complete
• B. All A., B. & C.
• C. Furnace control is easier
• D. Smaller height chimney can be used

Explanation: A forced-draft fan supplies air independently of chimney height, allowing a shorter chimney, better air regulation and generally more…

• A. 19
• B. 21
• C. 23
• D. 29

Explanation: Atmospheric air contains about 21% oxygen by volume but about 23% oxygen by mass because oxygen is heavier than nitrogen.

• A. 900-1000
• B. 400-500
• C. 1400-1500
• D. 1700-1800

Explanation: Gasification requires high temperature for the reactions of carbon with oxygen, air and steam, and is commonly conducted near 900 to…

• A. 4
• B. 96
• C. 20
• D. 40

Explanation: Using dry flue gas, excess air is approximately 100 times O₂ divided by 21 minus O₂: 100(4)/(21−4) ≈ 23.5%, which is around 20%.

• A. Sewage gas
• B. Refinery gas
• C. Producer gas
• D. Bagasse

Explanation: Producer gas is deliberately manufactured by gasifying solid fuel, so it is not a by-product fuel.

• A. Both A. and B.
• B. Affects the quality of steel produced as cracks develop on the surface while rolling the steel
• C. Contributes to its heating value
• D. Neither A. nor B.

Explanation: Sulphur contributes some heat on combustion, but in metallurgical coal it is undesirable because it causes hot shortness and surface…

• A. 900
• B. 4200
• C. 7500
• D. 2000

Explanation: Coke-oven gas contains mainly hydrogen, methane and carbon monoxide, giving it a heating value of roughly 4,000 to 4,500 kcal/Nm³.

• A. 8
• B. 12
• C. 22
• D. 36

Explanation: A blast-furnace coke blend generally requires a caking index near 20 to ensure that the coal particles soften, fuse and form strong coke.

• A. Has higher calorific value
• B. Is harder and stronger
• C. Is not subjected to washing
• D. Has low quantity of mineral matter

Explanation: Ash is mineral, non-combustible matter, so a high-ash coal has lower calorific value and greater mineral content.

• A. Coal tar
• B. Bitumen
• C. Molasses
• D. None of these

Explanation: Coal tar, bitumen and molasses are all commonly used as binders to hold coal particles together during briquetting.

• A. 12 hours
• B. 2-3 days
• C. One week
• D. Two weeks

Explanation: Beehive ovens operate slowly and typically require about two to three days for carbonisation, unlike modern by-product ovens that have…

• A. Speed of combustion of fuel
• B. Flame temperature achieved
• C. Calorific value of the fuel
• D. Heat transfer rate to the stock in the furnace

Explanation: Preheating combustion air raises flame temperature, accelerates combustion and improves heat transfer, but it cannot alter the chemical…

• A. CO2
• B. SO2
• C. Neither A. nor B.
• D. Both A. & B.

Explanation: KOH solution removes acidic gases by absorption and reaction, especially CO₂; it can also absorb SO₂.

• A. H2 content in the coke oven gas is more
• B. Aromatic content of tar is low
• C. Yield of ammonia is less
• D. Calorific value of the coke oven gas is lower

Explanation: High-temperature carbonisation produces coke-oven gas richer in hydrogen, while low-temperature carbonisation gives gas richer in heavier…

• A. Reduces the coking time
• B. Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot
• C. oven walls
• D. Increases the loss of fine coal dust from the ovens when charging
• E. None of these

Explanation: Free moisture absorbs heat and generates steam during carbonisation, which helps shield volatile products from cracking against the hot…

• A. Ignition temperature
• B. Calorific value
• C. Sulphur content
• D. Type (solid, liquid or gaseous)

Explanation: Solid fuels generally need more excess air than liquid fuels, while gaseous fuels need the least because mixing with air is more uniform.

• A. Gaseous fuels
• B. Solid fuels
• C. Liquid fuels
• D. Fat coals

Explanation: The Wobbe index compares the heating value of a gas with its specific gravity and is used to assess interchangeability of gaseous fuels.

• A. Inadequate ventilation
• B. All A., B. and C.
• C. Storage in large heaps with small surface to volume ratio
• D. Low temperature oxidation

Explanation: Coal can undergo slow, low-temperature oxidation, and inadequate ventilation or large heaps prevent the generated heat from escaping.

• A. Calorific value increases
• B. Swelling number increases
• C. Swelling number decreases
• D. Bulk density decreases

Explanation: Higher moisture dilutes the combustible matter and generally reduces coal swelling during heating.

• A. Tar
• B. Molasses
• C. Pitch
• D. Line

Explanation: Tar, pitch and molasses are common binders used to agglomerate coal particles into briquettes.