Mechanical Operations

401. Which of the following is not a wet classifier?

1. Sharpies super-centrifuge
2. Hydrocyclones
3. Dorr Oliver rake classifier
4. None of these

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402. Which of the following is not accomplished by agitation of liquids in agitators?

1. Dispersing gas in liquid
2. Blending of immiscible liquids
3. Dispersing immiscible liquid in form of emulsion
4. Suspending solid particles

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403. Which of the following is not an industrial screening equipment?

1. Sharpies centrifuge
2. Vibrating screen
3. Grizzly
4. Trommel

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404. Which of the following is not an ultrafine grinder (colloid mill)?

1. Micronizers
2. Agitated mills and fluid energy mills
3. Toothed roll crusher
4. Hammer mills with internal classification

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405. Which of the following is not categorised as a "mechanical operation”?

1. Agitation
2. Filtration
3. Size enlargement
4. Humidification

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406. Which of the following is not used as a filter medium in case of corrosive liquids?

1. Nylon
2. Glass cloth
3. Metal cloth of monel or stainless steel
4. Cotton fabric

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407. Which of the following is not used as a surface active agent in a flocculation operation?

1. Sodium silicate
2. Quartz
3. Lime
4. Alumina

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408. Which of the following is not used as filter aid?

1. Asbestos
2. Diatomaceous earth
3. Purified wood cellulose
4. Rice husk

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409. Which of the following is the hardest material?

1. Calcite
2. Quartz
3. Corundum
4. Gypsum

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410. Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid?

1. Sand bed filter
2. Plate and frame filter press
3. Vacuum filter
4. Batch basket centrifuge

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