All Free Chemical Engineering MCQs with Answers

• A. Caking
• B. Pulverised
• C. High ash
• D. Non-caking

Explanation: A travelling grate stoker continuously supports and moves lump coal through the furnace while air passes through the grate, making it…

• A. Fixed
• B. Moving
• C. Fluidised
• D. Entrained

Explanation: The Lurgi gasifier operates as a pressurised moving-bed, also called a fixed-bed or dry-bottom, gasifier in which coal descends while…

• A. The ratio of its percentage of fixed carbon to that of volatile matter
• B. Helpful in estimation of its rank
• C. Both A. and B.
• D. Neither A. nor B.

Explanation: Fuel ratio is defined as the percentage of fixed carbon divided by the percentage of volatile matter on the same basis.

• A. None of these
• B. Combustion of fire slacks on the grates
• C. Handling (e.g. when emptying wagons)
• D. Its pulverisation (as it requires more power)

Explanation: Free moisture makes coal sticky, obstructs its passage through pulverisers and increases the power needed for grinding.

• A. Uranium
• B. Plutonium
• C. Radium
• D. None of these

Explanation: Thermal reactors commonly use uranium, especially the fissile isotope uranium-235, because it can sustain a chain reaction with slow…

• A. 5000
• B. 25,000
• C. 10,000
• D. 15,000

Explanation: Propane has a heating value of roughly 22,000 kcal/Nm³ and butane about 29,000 kcal/Nm³, so an equal mixture is approximately 25,000…

• A. Calorific value
• B. Caking power
• C. Both A. & B.
• D. Neither A. nor B.

Explanation: More oxygen in coal generally indicates a lower-rank, more oxidised fuel, which lowers its calorific value and reduces its caking ability.

• A. Calorific value
• B. Difference in gross & net calorific value
• C. Sulphur content
• D. Higher C/H ratio

Explanation: Coal-tar fuels contain more aromatic and carbon-rich constituents than petroleum fuel oils, giving them a higher carbon-to-hydrogen ratio.

• A. None of these
• B. Ammoniacal cuprous chloride
• C. Pyrogallol solution
• D. KOH

Explanation: An Orsat apparatus absorbs carbon dioxide with KOH, oxygen with alkaline pyrogallol, and carbon monoxide with ammoniacal cuprous chloride.

• A. 11
• B. 2
• C. 20
• D. 38

Explanation: Burning 1 kg of carbon requires 32/12 = 2.67 kg of oxygen. Since air contains about 23% oxygen by mass, the theoretical dry-air…

• A. Fusion point of its ash
• B. Volatile matter content
• C. Caking capacity
• D. Inherent moisture content

Explanation: Fat coals are bituminous coals with a strong tendency to soften and agglomerate when heated, which is their high caking capacity.

• A. Either A. or B., depends on other factors
• B. Decreases
• C. Remain same
• D. Increases

Explanation: For a fixed mass of fuel, a higher C/H ratio means a greater fraction of carbon is present.

• A. Reduced NOx formation in flue gas
• B. All A., B. & C.
• C. High heat transfer rate
• D. Lower furnace operating temperature

Explanation: Fluidised-bed combustion operates at a lower, more uniform temperature, which suppresses thermal NOx formation, while intimate gas-solid…

• A. M40 > 78% and M10 < 10%
• B. M40 > 4% and M10 10% and M10 98% and M10 < 2%

Explanation: Strong metallurgical coke should resist both impact and abrasion, represented by a high M40 value and a low M10 value.

• A. Pulverised coal
• B. Caking coal
• C. Coking coal
• D. Non-caking coal

Explanation: Chain-grate stokers require coal that supports a permeable bed and burns progressively as it moves along the grate.

• A. Higher methane content and thus higher calorific value
• B. Higher carbon monoxide content
• C. Lower carbon dioxide content
• D. None of these

Explanation: High pressure favours methanation reactions, so a pressurised Lurgi gasifier produces more methane than an atmospheric gasifier.

• A. Cupola in foundries
• B. Iron blast furnace
• C. Sinter making
• D. Domestic ovens

Explanation: High-temperature carbonisation produces hard, strong coke with good porosity and resistance to crushing.

• A. 8
• B. 14
• C. 22
• D. 52

Explanation: Blast-furnace gas typically contains roughly 20 to 25% carbon monoxide, along with nitrogen, carbon dioxide and a small amount of…

• A. Lignite
• B. Bituminous
• C. Semi-anthracite
• D. Anthracite

Explanation: Coal maturity increases from lignite through bituminous and semi-anthracite to anthracite.

• A. All A., B. and C.
• B. Sulphur content is lower
• C. Flue gas has lower dew point thereby facilitating more waste heat recovery
• D. Emissivity factor is higher

Explanation: PCM generally has higher flame emissivity, lower sulphur content, and produces flue gas with a lower acid dew point than furnace oil.