Mass Transfer

351.Penetration theory relates the average mass transfer co-efficient (K) with diffusivity (D) as

1. K ∝D
2. K ∝√D
3. K ∝D1.5
4. K ∝D²

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352.Penetration theory states that the mass transfer co-coefficient is equal to (where, D_e is diffusivity and 't' is time)

1. (D_e.t)^1/2
2. (D_e/t)^1/2
3. (4D_e/πt)^1/2
4. (4D_e/t)

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353.Percentage saturation is _________ the relative saturation.

1. Always smaller than
2. Always greater than
3. Not related to
4. None of these

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354.Perforated plate towers are unique for solvent extraction because, they provide

1. Higher contact area
2. Better contact of the phase
3. Repeated coalescence & redispersion of the drop phase
4. None of these

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355.Physical absorption is

1. An irreversible phenomenon
2. A reversible phenomenon
3. Accompanied by evolution of heat
4. Both (B) and (C)

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356.Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.)

1. (1 + R_o) = R_o/R_i
2. (1 - R_o) = R_o/R_i
3. (1 + R_i) = R_o/R_i
4. (1 - R_i) = R_o/R_i

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357.Pick out the correct statement.

1. Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas
2. The 'Hatta number' is important in problems involving gas absorption without chemical reaction
3. For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion
4. Total reflux in case of distillation operation requires infinite number of plates for a binary system separation

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358.Pick out the system with minimum boiling azeotrope at 1 atm.

1. Benzene-toluene
2. Ethyl alcohol-water
3. Hydrochloric acid-water
4. All (A), (B) and (C)

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359.Pick out the wrong statement

1. Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance
2. In case of gas absorption, HETP is equal to HTU, when both the operating line & the equilibrium lines are parallel
3. Hatta number is important in case of gas absorption with chemical reaction
4. In actual practice, absorption is an endothermic process, while stripping is an exothermic process

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360.Pick out the wrong statement pertaining to leaching.

1. Fine solids cannot be leached in a Pachuca tank
2. Door classifier can be used for leaching of coarse solids
3. Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor
4. Very high temperature is not needed for the leaching of sugar beet

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