Mechanical Operations

351. Traces of liquid tar fog present in coke oven gas is separated using

1. Electrostatic precipitator
2. Cyclone separator
3. Strainer
4. None of these

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352. Trommels are revolving screens which normally operate in the range of _________ rpm.

1. 43862
2. 15 - 20
3. 40 - 50
4. 60 - 75

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353. Trommels employ _________ for screening of materials.

1. Fibrous cloth
2. Woven wire screen
3. Punched plate
4. None of these

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354. Trommels separate a mixture of particles depending on their

1. Size
2. Density
3. Wettability
4. Electrical & magnetic properties

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355. Tube mill compared to ball mill

1. Produces finer products
2. Is long in comparison with its diameter
3. Uses smaller balls
4. All (A), (B) & (C)

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356. Two particles are called to be equal settling, if they are having the same.

1. Size
2. Specific gravity
3. Terminal velocities in the same fluid & in the same field of force
4. None of these

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357. Ultra centrifuges are used for the separation of _________ solid particles.

1. Coarse
2. Fine
3. Colloidal
4. Dissolved

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358. Ultracentrifuges running at speeds upto 100000 rpm is normally used for the

1. Separation of isotopes based on their density or molecular weights difference
2. Concentration of rubber latex
3. Separation of cream from milk
4. Dewaxing of lubricating oil

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359. Ultrafine grinders operate principally by

1. Slow compression
2. Impact
3. Attrition
4. Cutting action

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360. Use of 'grinding aids' is done in _________ grinding.

1. Dry
2. Wet
3. Ultrafine
4. Intermediate

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