Mechanical Operations

331. The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle).

1. 6/D.ρ
2. 2/D.ρ
3. 4/D.ρ
4. 12/D.ρ

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332. The specific surface of spherical particles is proportional to (where, D_p = diameter of particle).

1. D²_p
2. D_p
3. 1/D_p
4. 1/D²_p

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333. The speed of a rotary drum vacuum filter may be about _________ rpm.

1. 1
2. 50
3. 100
4. 500

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334. The sphericity of a cylinder of 1 mm diameter and length 3 mm is

1. 0.9
2. 0.78
3. 0.6
4. 0.5

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335. The sphericity of a solid particle of cubical shape is

1. π
2. (π/6)1/3
3. (π/6)1/2
4. π/3

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336. The study on washability of coal is done by using the _________ technique.

1. Tabling
2. Elutriation
3. Heavy media separation
4. None of these

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337. The term 'angle of nip' is concerned with the operation of the _________ crushers.

1. Jaw
2. Roll
3. Gyratory
4. None of these

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338. The unit of filter medium resistance is

1. cm-1
2. gm/cm-1
3. cm/gm-1
4. gm-1

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339. The unit of specific cake resistance is

1. gm/cm₂
2. cm/gm
3. cm/gm₂
4. gm/gm

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340. The value of 'angle of nip' is generally about

1. 16°
2. 32°
3. 52°
4. 64°

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