# Food Processing Unit Operations Questions and Answers – Absorption Equipments

This set of Food Processing Unit Operations Multiple Choice Questions & Answers (MCQs) focuses on “Absorption Equipments”.

1. What is the soluble component called in absorption equipment?
a) Solute
b) Solvent
c) Liquid phase
d) Solution

Explanation: Absorption is the process by which a gas is dissolved in a liquid. The soluble component is called the solute and is transferred from the gas mixture to the liquid. The liquid consists of the solvent and absorbate.

2. Are these statements about the absorption true?
Statement 1: Operating pressure should be low for an absorber.
Statement 2: Operating temperature should be high for an absorber.
a) True, False
b) True, True
c) False, True
d) False, False

Explanation: Operating pressure should be high and temperature low for an absorber, to minimize stage requirements and absorbent flow rate to lower the equipment volume required to accommodate the gas flow.

3. What are the heat effects that cause temperatures to vary from point to point in a gas absorber?
a) The heat of solution
b) The heat of vaporization or condensation of the solvent
c) The heat of solution and the heat of vaporization or condensation of the solvent
d) No effect

Explanation: The heat effects that cause temperatures to vary from point to point in a gas absorber are heat of vaporization or condensation of the solvent, the heat of solution, the loss of sensible heat from the fluids to internal or external coils and the exchange of sensible heat between the gas and liquid phases.

4. At what conditions will the solute is absorbed more per stage or packing segment?
a) When L/G ratio is increased
b) When L/G ratio is decreased
c) When L/G ratio is negligible
d) When L/G ratio is reduced to very low level

Explanation: As the L/G ratio is increased, the operating line moves away from the equilibrium line and more solute is absorbed per stage or packing segment.

5. Is a scrubber and absorber same?
a) True
b) False

Explanation: If a component of the gas mix, transferred to liquid and is a gas at operating condition of mass transfer, then it is called as absorption. If a component transferred to liquid and is a vapor at operating condition of mass transfer, then it is called as scrubbing.
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6. What is stripping in absorption?
a) Operation of removing the absorbed solute from the solvent
b) Operation of removing the solvent from the absorbed solute
c) Operation of removing the unwanted solution
d) Operation of removing the catalyst

Explanation: Absorption is the process which is used for separating gas mixtures and removing impurities. It is used for recovering the valuable chemicals. The process of eliminating the absorbed solute from the solvent is known as stripping.

7. What is use of gas absorption column?
a) To study hydrodynamic process
b) To study absorption processes in packed columns
c) To study hydrodynamic and absorption processes in packed columns
d) To hold the gas

Explanation: The gas absorption column is a scale unit. It is intended to study the hydrodynamic and the absorption processes in the packed columns. In this system, it absorbs CO2 and ammonia from an air mixture in a watery solution that move along the column.

8. What is NTU?
a) Number of transfer units
b) Number of transport units
c) Neutral transfer units
d) Neutral tons units

Explanation: NTU is called as number of transfer units. It is the measure of the difficulty of the separation of the substance.The height of a transfer unit (HTU) is a measure of the effectiveness in separation of the packings for a particular separation process.

9. What is channeling in gas absorption?
a) Down in the bed, the liquid tends to flow toward the wall
b) At the top of the bed, the liquid tends to flow toward the wall
c) Down in the bed, the liquid tends to flow away from the wall
d) At the top of the bed, the liquid tends to flow away from the wall

Explanation: Down in the bed, the liquid tends to flow toward the wall. This condition is called as channeling. These occur in perforated trays or rely only on gas pressure to hold liquid on the tray, whereby the liquid outflows through the sieves at low gas rates.

10. What process takes place when water is used as absorbent?
a) Stripping
b) Dilution
c) Distillation
d) Dissolving

Explanation: When water is used as the absorbent, it is normally separated from the solute by distillation rather than stripping. Absorbers are generally used with strippers to permit regeneration and recycling of the absorbent.

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