All Free Chemical Engineering MCQs with Answers

• A. d1/3
• B. √d
• C. d2
• D. d2/3

Explanation: For laminar flow over a flat plate, boundary-layer thickness varies approximately as δ ∝ √x, where x is the distance from the leading…

• A. Creep
• B. Streamline
• C. Potential
• D. Boundary layer

Explanation: Potential flow is an ideal flow with zero vorticity and, for an inviscid fluid, no shear stress.

• A. Molten sodium (used as a coolant in Fast Breeder Reactor)
• B. Moderately viscous vegetable oil used in soap industry
• C. None of the above
• D. Thick molten soap at 80°C

Explanation: Centrifugal pumps are poorly suited to very viscous materials because viscosity causes large friction losses and reduces efficiency and…

• A. Circular
• B. Rectangular
• C. Triangular
• D. Trapezoidal

Explanation: The standard sharp-crested weir forms include rectangular, triangular or V-notch, and trapezoidal sections.

• A. One, which obeys Newton's law of viscosity
• B. Frictionless & incompressible
• C. Highly viscous
• D. None of these

Explanation: An ideal fluid is modeled as having zero viscosity, so it is frictionless, and constant density, so it is incompressible.

• A. Paddle
• B. Turbine
• C. Propeller
• D. All A., B. and C.

Explanation: A propeller is the standard axial-flow impeller because it moves fluid mainly parallel to the impeller shaft.

• A. Water surface
• B. None of these
• C. Centre of buoyancy
• D. Centre of gravity

Explanation: Metacentric height is the vertical distance between the metacentre and the centre of gravity.

• A. Pseudo-plastic
• B. Rheopectic
• C. Thixotropic
• D. Dilatant

Explanation: Paints and enamels commonly show pseudoplastic behaviour, meaning their apparent viscosity decreases as shear rate increases, making them…

• A. 2
• B. 4
• C. 8
• D. 5.5

Explanation: For geometrically similar centrifugal pumps, head varies as the square of speed: H₂/H₁ = (N₂/N₁)².

• A. 4
• B. 2100-4000
• C. 4000
• D. ∞

Explanation: The Reynolds number is Re = ρvD/μ, and an ideal fluid has zero viscosity, μ = 0.

• A. V/Vmax = (x/r)1/7
• B. V/Vmax = (r/x)1/7
• C. V/Vmax = (x.r)1/7
• D. None of these

Explanation: The one-seventh power law gives V/Vmax = (x/r)^(1/7) when x is the distance from the pipe wall and r is the pipe radius.

• A. Longer, if Metacentric height is increased
• B. None of these
• C. Dependent on the buoyant forces only
• D. Independent of the Metacentric height

Explanation: For small oscillations of a floating body, the period varies approximately as T ∝ 1/√(GM), so increasing metacentric height makes the…

• A. Newtonian
• B. Dilatant
• C. Pseudo-plastic

Explanation: For steady laminar flow of a Newtonian fluid, the Hagen–Poiseuille relation gives Q ∝ D⁴ at fixed pressure drop and length.

• A. 4
• B. > 12.5
• C. < 10

Explanation: Capillary rise or depression becomes negligible when the manometer tube is sufficiently large, conventionally above about 12.5 mm in…

• A. Circulation around the body is essentially required
• B. The body should be stream lined
• C. The body should be bluff body
• D. The main stream velocity must approach the velocity of sound in that fluid medium

Explanation: Lift is associated with a pressure difference produced by circulation around the body, as in the circulation theory of lift.

• A. Reduction of pressure below vapour pressure
• B. Adverse pressure gradient
• C. Reduction of pressure gradient to zero
• D. Reduction of boundary layer thickness to zero

Explanation: An adverse pressure gradient means pressure increases in the direction of flow, slowing the boundary-layer fluid until it can reverse near…

• A. Angular velocity
• B. None of these
• C. Specific volume
• D. Fanning friction factor

Explanation: The Fanning friction factor is a ratio of wall shear stress to dynamic pressure, so its units cancel.

• A. Linear with radius for both laminar & turbulent flow
• B. Linear with radius for laminar flow only
• C. Linear with radius for turbulent flow only
• D. Parabolic with radius for both laminar & turbulent flow

Explanation: A momentum balance on a circular tube gives shear stress proportional to the distance from the tube axis, regardless of whether the flow…

• A. Cc . Cv
• B. Cc . Cd
• C. Cv . Cd
• D. Cd/Cv

Explanation: The discharge coefficient is defined as actual discharge divided by theoretical discharge, so the ratio is Cd.

• A. Placed farther from the wall
• B. Near each other
• C. Not affected by other particles and the wall
• D. None of these

Explanation: Hindered settling occurs at sufficiently high particle concentration that neighbouring particles interfere with one another and displace…