Mechanical Operations

251. Screw conveyors are

1. Run at very high rpm
2. Suitable for sticky materials
3. Suitable for highly abrasive materials
4. All (A), (B) and (C)

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252. Sedimentation on commercial scale occurs in

1. Classifiers
2. Thickeners
3. Rotary drum filters
4. Cyclones

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253. Separation of a suspension or slurry into a supernatant clear liquid (free from particles) and a thick sludge containing a high concentration of solid is called

1. Classification
2. Sedimentation
3. Clarification
4. Decantation

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254. Separation of isotopes is generally done using a/an _________ centrifuge.

1. Ultra
2. Disk-bowl
3. Both (A) & (B)
4. Neither (A) nor (B)

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255. Separation of materials into products based on the difference of their sizes is called

1. Sizing
2. Sorting
3. Classification
4. Flocculation

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256. Separation of materials of the same density based on their sizes by using then-different rates of flow is called

1. Sorting
2. Sizing
3. Flocculation
4. Elutriation

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257. Separation of particles of various sizes, shapes and densities by allowing them to settle in a fluid is called

1. Classification
2. Froth floatation
3. Thickening
4. Clarification

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258. Separation of solid particles based on their densities is called

1. Sizing
2. Sorting
3. Clarification
4. Dispersion

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259. Separation of solid suspended in liquid into a supernatant clear liquid and a denser slurry employs a process termed as the

1. Coagulation
2. Flocculation
3. Sedimentation
4. Clarification

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260. Shape factor for a cylinder whose length equals its diameter is

1. 1.5
2. 0.5
3. 1
4. 2

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