Mechanical Operations

361. Use of baffles in agitators help in minimising the _________ tendency.

1. Swirling
2. Vortexing
3. Both (A) & (B)
4. Neither (A) nor (B)

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362. Use of grinding aids results in the

1. Enhanced production rate
2. Finer products
3. Both (A) & (B)
4. Neither (A) nor (B)

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363. Vacuum filter is most suitable for the

1. Removal of fines from liquid
2. Liquids having high vapour pressure
3. Liquids of very high viscosity
4. None of these

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364. Vacuum is applied in _________ zone, in case of a general type continuous rotary drum vacuum filter.

1. Filtering
2. Washing
3. Drying
4. All (A), (B) & (C)

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365. Velocity of a small particle of diameter 'D_p' at a distance 'r' from the rotational axis of a cyclone rotating at an angular speed 'ω' is given by (the other symbols are as per standard notation).

1. [(D_p/18). (ρs - ρ/μ)] ω²r
2. [(D_p²/18). (ρs - ρ/μ)] ω²r
3. [(D_p/18). (ρs - ρ/μ)] ω²r²
4. [(D_p²/18). (ρs - ρ/μ)] ω²r

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366. Vertical transportation of materials can be done by a/an

1. Apron conveyor
2. Pneumatic conveyor
3. Bucket elevator
4. Both (B) & (C)

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367. Vibrating screens are used for handling large tonnages of materials. The vibrating motion is imparted to the screening surface by means of

1. Electromagnets
2. Cams or eccentric shafts
3. Unbalanced flywheels
4. Either (A), (B) or (C)

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368. Vibrating screens have capacity in the range of _________ tons/ft2 .mm mesh size.

1. 0.2 to 0.8
2. 5 to 25
3. 50 to 100
4. 100 to 250

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369. Washability curve based on float and sink test enables an assessment to be made of the possibility of cleaning a coal fraction based on the

1. Density separation
2. Differential wettability
3. Size
4. Volatile matter content

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370. Weber number is significant and is concerned with the

1. Solid-liquid mixing
2. Liquid-liquid mixing
3. Dispersion of liquid in liquid
4. Suspension of solid in liquid

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