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. Carbonisation
- B. Gasification
- C. Coalification
- D. Deoxidation
Explanation: Heating coal in the absence of air decomposes it into coke, tar, gas and other products, a process called carbonisation.
Correct answer: Carbonisation- A. Coke oven gas
- B. Water gas
- C. Blast furnace gas
- D. Natural gas
Explanation: The gross-to-net calorific value difference mainly represents the latent heat of water formed from hydrogen combustion.
Correct answer: Blast furnace gas- A. Low fusion point of ash
- B. High ash content
- C. High sulphur
- D. None of these
Explanation: A good coal should have low ash and sulphur and ash with a high fusion temperature, so that ash does not form troublesome deposits or…
Correct answer: None of these- A. 80 and 97
- B. 95 and 100
- C. 40 and 70
- D. 25 and 97
Explanation: Metallurgical coke is expected to resist breakage, giving a shatter index of roughly 80% on the 2-inch screen and 97% on the 0.5-inch…
Correct answer: 80 and 97- A. Thickness of plastic layer
- B. Caking index
- C. Swelling index
- D. Gray-king index
Explanation: The caking index directly indicates coal's tendency to soften and bind neighbouring particles during heating.
Correct answer: Caking index- A. Tar
- B. Benzol
- C. Ammonia
- D. None of these
Explanation: Direct, indirect and semi-direct by-product recovery classifications refer to the method used to recover ammonia from coal-carbonisation…
Correct answer: Ammonia- A. All A., B. and C.
- B. Storage in compressed piles
- C. Absence of porous or friable particles
- D. Storage in large heaps
Explanation: Large coal heaps retain the heat generated by slow oxidation, causing the temperature and oxidation rate to rise further.
Correct answer: Storage in large heaps- A. Decreases
- B. Increases
- C. Remain same
- D. May increase or decrease depending on the type of fuel
Explanation: Increasing the C/H ratio increases the carbon available per unit mass of fuel, so more carbon is converted to CO2 under comparable…
Correct answer: Increases- A. The gaseous fuel before combustion decreases
- B. Combustion air decreases
- C. Either the fuel or the air or both, increases
- D. Either the fuel or the air does not affect
Explanation: Preheating the fuel, the combustion air, or both supplies sensible heat before reaction, so less heat is needed to raise the products to…
Correct answer: Either the fuel or the air or both, increases- A. All A., B. and C.
- B. Methane
- C. Unsaturated hydrocarbons
- D. Hydrogen
Explanation: As carbonisation continues at high temperature, methane and unsaturated hydrocarbons undergo further cracking, while hydrogen formation…
Correct answer: Hydrogen- A. Pulverisation
- B. Washing
- C. Transportation and handling
- D. Storage
Explanation: Free or force moisture makes coal stick to surfaces, obstructs feeders, and increases the energy required for size reduction.
Correct answer: Pulverisation- A. Are soft & friable (poor strength and size stability)
- B. Require longer time of carbonisation as ash offers resistance to heat transfer
- C. Produce larger quantity of coke oven gas
- D. None of these
Explanation: Ash is largely mineral matter and acts as a thermal barrier inside the coal charge, so heat penetrates more slowly and carbonisation takes…
Correct answer: Require longer time of carbonisation as ash offers resistance to heat transfer- A. Humidity of combustion air
- B. Moisture content of fuel
- C. Both A. and B.
- D. The water formed by combustion reaction
Explanation: Moisture loss in a combustion calculation includes water entering with the fuel and water vapour entering with humid combustion air.
Correct answer: Both A. and B.- A. 550
- B. 750
- C. 950
- D. 1150
Explanation: In proximate analysis, volatile matter is measured by heating the coal without air at about 950°C for seven minutes.
Correct answer: 950- A. Higher amount of methane
- B. Both A. and B.
- C. Lower amount of hydrogen
- D. Higher amount of both methane and hydrogen
Explanation: The high pressure in a Lurgi gasifier favours methanation, giving more CH₄, and generally produces less H₂ than the atmospheric-pressure…
Correct answer: Both A. and B.- A. 300
- B. 2000
- C. 5000
- D. 10000
Explanation: Blast-furnace gas production is typically around 2,000 Nm³ per tonne of pig iron, although the exact value varies with furnace operation…
Correct answer: 2000- A. Less air for combustion
- B. Correct amount of air for combustion
- C. Too much air for combustion
- D. Pulverised coal in boilers
Explanation: Dense white plume generally indicates water vapour condensed in the cooler flue gas, commonly associated with excess air carrying…
Correct answer: Too much air for combustion- A. Producer gas
- B. Coal gas from underground gasification of coal
- C. None of these
- D. Refinery gases
Explanation: Refinery gases contain substantial amounts of readily combustible hydrocarbons such as methane, ethane, propane and butanes, giving them a…
Correct answer: Refinery gases- A. Coke even gas yield increases
- B. Tar yield increases
- C. Hydrogen percentage in the coke oven gas decreases
- D. Methane percentage in the coke oven gas increases
Explanation: Increasing carbonisation temperature promotes secondary cracking and gas formation, so coke-oven gas yield increases.
Correct answer: Coke even gas yield increases- A. Fixed carbon and heating value around 132 BTU/1b
- B. Ash and heating value around 13, 200 BTU/1b
- C. Fixed carbon and having a heating value around 13, 200 BTU/1b
- D. None of these
Explanation: The ASTM coal-rank notation 64-132 indicates approximately 64% fixed carbon and a heating value near 13,200 Btu/lb.
Correct answer: Fixed carbon and having a heating value around 13, 200 BTU/1b