All Free Chemical Engineering MCQs with Answers

• A. Both A. & B.
• B. Emitter
• C. Absorber
• D. Neither A. nor B.

Explanation: A perfect black body absorbs all incident radiation and, at a given temperature, emits the maximum possible radiation.

• A. Biot
• B. Nusselt
• C. Reynolds
• D. Prandtl

Explanation: The heat-transfer j-factor is a dimensionless correlation commonly expressed as a function of Reynolds number, often with a Prandtl-number…

• A. Liquid depth over the heating surface
• B. Solution being evaporated
• C. All A., B. and C.
• D. Pressure difference between the steam chest and the vapor space above the boiling liquid

Explanation: The effective temperature drop includes the steam-to-vapour pressure difference, boiling-point elevation caused by the solution, and…

• A. 0.2
• B. 0.4
• C. 0.6
• D. 0.8

Explanation: For a turbulent core at a Prandtl number around 0.6, turbulent eddy transport is much greater than molecular conduction, so direct…

• A. There is no risk of contamination
• B. Heat transfer co-efficient are high
• C. There is no mist formation
• D. Cost of equipment is lower

Explanation: Indirect exchangers keep the two fluids separated by a wall, preventing mixing and contamination.

• A. Dowtherm
• B. Air
• C. Water
• D. Molten sodium

Explanation: Air has a much lower thermal conductivity and convective heat-transfer coefficient than water, molten sodium, or Dowtherm.

• A. Long vertical evaporator
• B. Horizontal tube evaporator
• C. Agitated film evaporator
• D. Calandria vertical tube evaporator

Explanation: An agitated film evaporator uses mechanical agitation to force and renew the liquid film over the heating surface, making it suitable for…

• A. Logarithmic
• B. Arithmetic
• C. Geometric
• D. Either A., B. or C.

Explanation: Radial conduction through a cylinder varies with radius, so the appropriate area is based on the logarithmic mean radius or logarithmic…

• A. Re.Gz
• B. Nu, Gz
• C. Nu, Pr, Re
• D. Nu, Pr

Explanation: For laminar flow with developing thermal conditions, the Nusselt number is commonly correlated with the Graetz number, which combines…

• A. Heat the water from 0°C to 100°C
• B. To superheat the steam
• C. Evaporate the water
• D. Data insufficient, can't be predicted

Explanation: The latent heat required to vaporise water at 1 atm is about 2257 kJ/kg, much greater than the sensible heating from 0 to 100°C or the…

• A. Called the view factor
• B. Expressed in terms of radians
• C. Proportional to the square of the distance between surfaces
• D. Called the angle of vision

Explanation: The solid angle subtended by a finite surface at a radiating element is commonly called its angle of vision.

• A. Both A. & B.
• B. Dissolved O2
• C. CO2
• D. Neither A. nor B.

Explanation: Carbon dioxide dissolves in condensate to form carbonic acid, while dissolved oxygen promotes oxidation and pitting.

• A. 0.2 D
• B. 0.5 D
• C. 0.66 D
• D. 0.80 D

Explanation: Baffles should not be placed too close because this restricts shell-side flow and increases pressure drop; a usual minimum spacing is…

• A. Multipass fixed tube sheet
• B. None of these
• C. Single pass fixed tube sheet
• D. U-tube

Explanation: U-tube exchangers allow the tubes to expand and contract freely because each tube bends at the U-bend.

• A. Both B. & C.
• B. Refract
• C. Reflect
• D. Absorb or emit

Explanation: An ideal black body absorbs all incident radiation and therefore neither reflects nor transmits it; textbook treatments often express the…

• A. 970
• B. 180
• C. 3.97
• D. Data insufficient, can't be predicted

Explanation: For water, the specific heat is approximately 1 BTU/(lb·°F). Thus, sensible heat absorbed is 1 × (212 − 32) = 180 BTU.

• A. Kirchoff's
• B. Fourier's
• C. Planck's
• D. None of these

Explanation: Integrating Planck's spectral blackbody radiation law over all wavelengths gives the Stefan-Boltzmann law.

• A. 2 √(A1 . A2)
• B. √(A1 + A2)
• C. ½ √(A1 . A2)
• D. √(A1 . A2)

Explanation: The geometric mean of two positive quantities is the square root of their product.

• A. 2
• B. 1/2
• C. 4
• D. 1/4

Explanation: In a multipass shell-and-tube exchanger, the tube-side return loss is commonly taken as four velocity heads.

• A. Liquid metal
• B. Aqueous solution
• C. Water
• D. Lube oil

Explanation: Prandtl number is the ratio of momentum diffusivity to thermal diffusivity, and liquid metals have exceptionally high thermal diffusivity.