All Free Chemical Engineering MCQs with Answers

• A. Impact
• B. Attrition
• C. Cutting
• D. Compression

Explanation: A colloid mill uses intense shearing and rubbing between closely spaced surfaces, so attrition is the main size-reduction mechanism.

• A. Important in the beginning of filtration
• B. Decreased with the time of filtration
• C. None of these
• D. Independent of pressure drop

Explanation: Cake resistance is initially small because little cake has formed, then increases as solids accumulate on the filter medium.

• A. Pebble
• B. Tube
• C. Rod
• D. Compartment

Explanation: A compartment mill is divided by perforated partitions so that coarse grinding occurs in the first compartment and progressively finer…

• A. D/V
• B. AD/V
• C. A/V
• D. √(AD/V)

Explanation: The specific-surface shape factor is dimensionless and is commonly expressed as AD/V, where A is particle surface area, D is the…

• A. Basic slags
• B. Non-metallic ores
• C. Metalliferous ores
• D. Asbestos & mica

Explanation: Metalliferous ores are commonly reduced using crushing rolls, rod mills, and ball mills because these machines can handle hard, abrasive…

• A. Flight
• B. Ribbon
• C. Belt
• D. Drag or slat

Explanation: Drag or slat conveyors are robust and suited to heavy, abrasive, hot, and irregular solids such as furnace ash.

• A. Gyratory crusher
• B. Fluid energy mill
• C. Rod mill
• D. Ball mill

Explanation: A gyratory crusher combines the fixed-jaw crushing principle with a continuously gyrating crushing surface, giving more continuous action…

• A. φs = Vp/dpsp
• B. φs = 6 Vp/dpsp
• C. φs = 6 dpSp/Vp
• D. φs = dpSp/Vp

Explanation: Sphericity compares the surface area of a volume-equivalent sphere, πd_p², with the actual particle area S_p.

• A. 0
• B. ∞
• C. 0 to 1
• D. 1

Explanation: The cake compressibility coefficient ranges from 0 for an incompressible cake to 1 for an absolutely compressible cake.

• A. Toothed roll crusher
• B. Agitated mills and fluid energy mills
• C. Micronizers
• D. Hammer mills with internal classification

Explanation: Ultrafine grinders include micronizers, fluid-energy or agitated mills, and classified hammer mills.

• A. Thickness
• B. Speed
• C. Length
• D. None of these

Explanation: Belt-conveyor capacity equals the cross-sectional area of material on the belt multiplied by belt speed.

• A. Jaw crushers
• B. Gyratory crushers
• C. Rod mills
• D. Smooth roll crushers

Explanation: Rod mills primarily use impact and attrition between rods and particles rather than compression as the main size-reduction action.

• A. Is a ball mill
• B. Employs flints or ceramic pebbles as the grinding medium
• C. Is a tube mill lined with ceramic or other non-metallic liner
• D. Both B. and C.

Explanation: A pebble mill is a tube mill lined with a non-metallic material and uses flint or ceramic pebbles instead of metallic balls.

• A. Peclet
• B. Weber
• C. Brinkman
• D. Schmidt

Explanation: The ratio vL/D compares convective transport over the mixer length with axial diffusive mixing, which is the Peclet number.

• A. Filter cloth
• B. Embedded particles in the septum
• C. Filter cloth and the embedded particle collectively
• D. None of these

Explanation: Filter-medium resistance includes the resistance of the cloth or septum together with particles lodged in its pores.

• A. Entire process
• B. Final stages
• C. Early stages
• D. None of these

Explanation: At the beginning, the cake is thin and its resistance is small, so the fixed resistance of the filter medium is relatively important.

• A. Explosive
• B. Catalyst
• C. Filter medium
• D. Filter aid

Explanation: Diatomaceous earth consists of porous silica-rich remains of diatoms and is commonly added to form a permeable cake.

• A. Gravity sand
• B. Plate and frame
• C. Vacuum leaf
• D. Rotary vacuum

Explanation: Gravity sand filters are widely used in potable-water treatment because water passes slowly through sand, which traps suspended…

• A. Fibrous cloth
• B. Punched plate
• C. Woven wire screen
• D. None of these

Explanation: Trommels are rotating cylindrical screens commonly fitted with punched plates, whose openings classify materials by size.

• A. Impact
• B. Attrition
• C. Compression
• D. Cutting

Explanation: A gyratory crusher reduces size by compression between a gyrating mantle and the fixed concave surface.