Practice Test: Question Set - 03
1. Sphericity of raschig ring (whose length and diameter are equal) is
- (A) > 1
- (B) < 1
- (C) 1
- (D) 2
2. For efficient grinding, ball mills must be operated
- (A) At a speed less than the critical speed
- (B) At a speed more than the critical speed
- (C) At a speed equal to the critical speed
- (D) With minimum possible small balls
3. Which of the following gives the crushing energy required to create new surface?
- (A) Taggarts rule
- (B) Fick's law
- (C) Rittinger's Law
- (D) None of these
4. Rittinger's number designates the new surface created per unit mechanical energy absorbed by the material being crushed. Larger value of Rittinger's number of a material indicates its
- (A) Easier grindability
- (B) Poor grindability
- (C) High power consumption in grinding
- (D) None of these
5. The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.
- (A) Vacuum
- (B) Sand
- (C) Plate & frame
- (D) Rotary
6. Carbon black is pulverized in a
- (A) Hammer crusher
- (B) Ball mill
- (C) Roll crusher
- (D) Gyratory crusher
7. Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for
- (A) British standard screens
- (B) German standard screens (DIN 1171) etc
- (C) American standard screens (ASTM and Tyler standard screens)
- (D) All (a), (b) and (c)
8. Which of the following is a vacuum filter?
- (A) Filter press
- (B) Rotary disc filter
- (C) Batch basket centrifuge
- (D) Tank filter (Nutsche filter)
9. In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing.
- (A) Secondary
- (B) Fine
- (C) Primary
- (D) Ultrafine
10. A fluid energy mill is used for
- (A) Cutting
- (B) Grinding
- (C) Ultra grinding
- (D) Crushing
11. __________ centrifuge is the most suitable for separation of non-friable crystals.
- (A) Tubular bowl
- (B) Disc-bowl
- (C) Perforated horizontal basket continuous
- (D) Suspended batch basket
12. Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid?
- (A) Sand bed filter
- (B) Plate and frame filter press
- (C) Vacuum filter
- (D) Batch basket centrifuge
13. Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is
- (A) > 10
- (B) < 10
- (C) > 100
- (D) < 100
14. The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake)
- (A) ∝ ΔP
- (B) ∝ 1/ ΔP
- (C) ∝ √ΔP
- (D) Independent of ΔP
15. A __________ employs a set of screen across a flow channel for the separation of dirt/rust from a flowing liquid stream.
- (A) Thickener
- (B) Classifier
- (C) Strainer
- (D) Clarifier
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