All Free Chemical Engineering MCQs with Answers

• A. Increases capacity
• B. Requires more energy
• C. Gives less wear on chamber walls
• D. Complicates handling of the product

Explanation: Water helps distribute solids and remove heat in wet grinding, commonly allowing a higher throughput than dry grinding.

• A. Over-sizes are present in undersize fraction
• B. Screen is plugged with solid particles
• C. Under-sizes are retained in oversize fraction
• D. Screen capacity is abruptly increased

Explanation: Blinding occurs when openings in a screen become blocked by particles, preventing material from passing through them and reducing…

• A. Pressure filter
• B. Vacuum filter
• C. Centrifugal filter
• D. Gravity filter

Explanation: A vacuum lowers the liquid’s boiling point, so a volatile liquid can evaporate or flash during vacuum filtration.

• A. Sharpies centrifuge
• B. Propeller agitator
• C. Boundary mixer
• D. None of these

Explanation: A boundary mixer applies intense shearing and kneading action, making it suitable for processing rubber scrap and preparing rubber…

• A. Strains
• B. Gravity settler
• C. Coagulant
• D. Clarifier

Explanation: Strainers remove dirt and other suspended solid particles mechanically as fluid passes through a screen or mesh.

• A. π
• B. (π/6)1/3
• C. (π/6)1/2
• D. π/3

Explanation: For a cube, sphericity is the surface-area-equivalent sphere ratio, which reduces to (/)^(1/3) = (π/6)^(1/3).

• A. S
• B. 1/R
• C. All A., B. & C.
• D. 1/μ

Explanation: Darcy’s filtration relation gives rate proportional to SA/(μR) for a fixed pressure drop, so increasing filter area or decreasing…

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

Explanation: A fluid energy mill uses high-velocity jets of gas to cause particle-to-particle impact and attrition, producing ultrafine particles.

• A. 1 to 2°
• B. 2 to 5°
• C. 5 to 10°
• D. 10 to 15°

Explanation: A concentrating table is normally set at a small inclination, commonly about 2 to 5°, so the flowing water and shaking action can separate…

• A. Produces finer products
• B. Is long in comparison with its diameter
• C. Uses smaller balls
• D. All A., B. & C.

Explanation: A tube mill is a long, narrow form of ball mill, and its longer grinding path and smaller balls allow it to produce a finer product.

• A. All A., B. and C.
• B. Rotor speed
• C. Clearance between hammer & grinding plates
• D. Feed rate

Explanation: Hammer-crusher product size is influenced by feed rate, rotor speed, and the clearance between the hammers and grinding plates.

• A. Rod mills
• B. Hammer mills
• C. Gyratory crushers
• D. Crushing rolls

Explanation: Hammer mills are suitable for reducing relatively soft, brittle, or fibrous materials such as asbestos and mica.

• A. Its speed
• B. Its ball load
• C. All A., B. and C.
• D. The density of the material being ground

Explanation: Ball-mill power consumption varies with mill speed and ball load, while material density also affects the load and energy required for…

• A. 2
• B. √3
• C. 1.5
• D. √2

Explanation: In the Taylor standard sieve series, successive sieve dimensions differ by a factor of √2.

• A. Centrifugation
• B. Flocculation
• C. Dispersion
• D. Sedimentation

Explanation: When separation is produced by a force greater than gravitational force, such as centrifugal force, the operation is called…

• A. Classification
• B. Sedimentation
• C. Clarification
• D. Decantation

Explanation: Sedimentation separates a suspension by gravity into a clarified upper liquid and a settled sludge or sediment.

• A. Cube of impeller diameters
• B. Viscosity of the liquid
• C. Density of the liquid
• D. Square of rotational speed

Explanation: For laminar agitation, power is proportional to viscosity, the square of rotational speed, and the cube of impeller diameter, but it is…

• A. Sand
• B. Press
• C. Rotary
• D. Leaf

Explanation: A Moore filter is a leaf filter in which filtration occurs through one or more porous leaves immersed in the slurry.

• A. Resistance decreases with time
• B. Rate of filtration is constant
• C. Rate of filtration increases with time
• D. Rate of filtration decreases with time

Explanation: At constant pressure, the growing filter cake continuously increases filtration resistance.

• A. Corundum
• B. Quartz
• C. Calcite
• D. Gypsum

Explanation: Corundum has a Mohs hardness of 9, higher than quartz at 7, calcite at 3, and gypsum at 2.