Mechanical Operations problems
- 1. All resistances during washing of cake
Options- A. increases
- B. decreases
- C. remain constant
- D. none of these Discuss
Correct Answer: remain constant
- 2. Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are
Options- A. carbonates
- B. sulphates
- C. silicates & phosphates
- D. bi-carbonates Discuss
Correct Answer: silicates & phosphates
- 3. Temperature of the product during ultrafine grinding
Options- A. increases
- B. decreases
- C. remains constant
- D. may increase or decrease ; depends on the material being ground Discuss
Correct Answer: increases
- 4. __________ mills are termed as impactors.
Options- A. Hammer
- B. Cage
- C. Rolling-compression
- D. none of these Discuss
Correct Answer: Hammer
- 5. 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
Options- 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). Discuss
Correct Answer: all (a), (b) and (c).
- 6. Size measurement of ultrafine particles can be best expressed in terms of
Options- A. centimetre
- B. screen size
- C. micron
- D. surface area per unit mass Discuss
Correct Answer: surface area per unit mass
- 7. Which is a secondary crusher for a hard & tough stone?
Options- A. Jaw crusher
- B. Cone crusher
- C. Impact crusher
- D. Toothed roll crusher Discuss
Correct Answer: Cone crusher
- 8. Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)
Options- A. 0.5 D
- B. D
- C. 1.5 D
- D. 2 D Discuss
Correct Answer: D
- 9. A __________ mixer resembles a ball mill without balls.
Options- A. banbery
- B. pug mill
- C. tumbling
- D. pan Discuss
Correct Answer: tumbling
- 10. Tank filter (e.g., Nutsch filter) is
Options- A. a high pressure filter.
- B. a continuous filter.
- C. used for small scale filtration work.
- D. a leaf filter. Discuss
Correct Answer: used for small scale filtration work.
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