All Free Chemical Engineering MCQs with Answers
Every Chemical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
6,983 questions · page 262 of 350
- A. 2
- B. 8
- C. 10
- D. 40
Explanation: For a cylinder, the critical insulation radius is r_c = k_insulation/h = 0.1/5 = 0.02 m, or 2 cm.
Correct answer: 2- A. Dryness
- B. Moisture content
- C. Coolness
- D. Latent heat
Explanation: Dew-point temperature is the temperature at which the air becomes saturated and condensation begins, so it reflects the moisture content…
Correct answer: Moisture content- A. 370
- B. 340
- C. 320
- D. 300
Explanation: Newton’s law of cooling makes the temperature excess above the bath temperature fall by the same ratio in equal time intervals.
Correct answer: 370- A. 5 to 10
- B. 15 to 25
- C. 75 to 80
- D. 45 to 50
Explanation: Human comfort near 22 to 27°C generally requires moderate relative humidity, about 45 to 50 percent.
Correct answer: 45 to 50- A. Re0.8, Re0.5
- B. Re0.8, Re-0.5
- C. Re0.5, Re0.8
- D. Re-0.8, Re0.5
Explanation: For turbulent flow, the usual heat-transfer correlation gives Nu proportional to Re^0.8, while for laminar flow the dependence is…
Correct answer: Re0.8, Re0.5- A. 1/k
- B. k
- C. k2
- D. 1/k2
Explanation: Thermal diffusivity is given by α = k/(ρCp), so with density and heat capacity fixed it is directly proportional to thermal conductivity…
Correct answer: k- A. Boiler
- B. Evaporator
- C. Condenser
- D. All A. B. & C.
Explanation: A condenser removes latent heat from vapour as it changes into liquid, so heat is released to the cooling medium.
Correct answer: Condenser- A. Evaporative capacity
- B. Evaporation efficiency
- C. Thermal efficiency
- D. Steam load
Explanation: Evaporative capacity is the mass of water converted into steam per unit mass of fuel burned, usually expressed as kg/kg of fuel.
Correct answer: Evaporative capacity- A. Providing support for the tubes
- B. Both A & B
- C. Improving heat transfer
- D. Preventing the fouling of tubes & stagnation of shell side fluid
Explanation: Shell-side baffles support the tubes and force the fluid across them, increasing turbulence and heat-transfer coefficient.
Correct answer: Both A & B- A. Less
- B. More
- C. Equal
- D. Unpredictable
Explanation: For flow over a heated flat plate, Pr > 1 means momentum diffuses faster than heat, so the thermal boundary layer is thinner than the…
Correct answer: Less- A. Enthalpy
- B. Relative humidity
- C. Wet bulb temperature
- D. Dew point temperature
Explanation: Without condensation, cooling removes sensible heat while the humidity ratio remains constant; consequently, the water-vapour partial…
Correct answer: Dew point temperature5232. Which of the following commonly used condenser tube materials has the lowest thermal conductivity ?
- A. Stainless steel
- B. Admiralty brass
- C. Aluminium brass
- D. Titanium
Explanation: Stainless steel has much lower thermal conductivity than admiralty brass, aluminium brass and titanium, so it offers the greatest…
Correct answer: Stainless steel- A. 200 BTU/minute
- B. 50 kcal/minute
- C. 50 kJ/sec
- D. 3.5 KW
Explanation: One ton of refrigeration is approximately 200 Btu/min, 50 kcal/min or 3.5 kW.
Correct answer: 50 kJ/sec- A. Both specific humidity & dry bulb temperature increases
- B. Both specific humidity & dry bulb temperature decreases
- C. Specific humidity decreases & dry bulb temperature increases
- D. Specific humidity increases & dry bulb temperature decreases
Explanation: Chemical dehumidification uses a hygroscopic absorbent to remove water vapour from air, reducing specific humidity.
Correct answer: Specific humidity decreases & dry bulb temperature increases- A. (r2 - r1)/r1. r2
- B. r1. r2/(r2 - r1)
- C. (r2 + r1)/r1. r2
- D. r1. r2/(r2 + r1)
Explanation: For steady radial conduction through a hollow sphere, heat flow is proportional to the spherical conductance factor r1r2/(r2 − r1).
Correct answer: r1. r2/(r2 - r1)- A. Feed water pump
- B. Feed check valve
- C. Blow off cock
- D. Stop valve
Explanation: A feed-water pump supplies water to the boiler and is therefore an accessory.
Correct answer: Feed water pump- A. Compared to the mass flow rate of cooling water, the rate of condensation of steam is
- B. invariably smaller
- C. Maintaining vacuum on tube side is more difficult than that on the shell side
- D. Condenser can act as a storage unit for condensed steam
- E. because of its lower specific volume compared to steam
- F. Water velocity can be increased conveniently to increase the overall heat transfer co-efficient
Explanation: Cooling water is placed inside the tubes because its velocity can be increased conveniently, which raises the tube-side heat-transfer…
Correct answer: Water velocity can be increased conveniently to increase the overall heat transfer co-efficient- A. Saturation
- B. Dry bulb
- C. Wet bulb
- D. Dew point
Explanation: In an ideal evaporative cooling tower, water can theoretically approach the entering air's wet-bulb temperature.
Correct answer: Wet bulb- A. Conduction
- B. Convection
- C. Both A. & B.
- D. Radiation
Explanation: In a high-pressure boiler furnace, the flame and hot combustion gases transfer most of their energy to the water-wall tubes by radiation.
Correct answer: Radiation- A. Sensible heat is removed and the latent heat is added
- B. Sensible heat is added
- C. Latent heat is removed
- D. Sensible heat is added and latent heat is removed
Explanation: During evaporative cooling, sensible heat is removed from the air while water evaporates and adds latent heat to it.
Correct answer: Sensible heat is removed and the latent heat is added