# Mass Transfer Questions and Answers – Humidification-Operation

This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on “Humidification-Operation”.

1. Humidification is a
a) Mass transfer operation
b) Heat transfer operation
c) Simultaneous heat and mass transfer
d) Neither mass and heat transfer operation

Explanation: From the gas heat as well as the solute components are removed.

2. In humidification the gas is ____________ in the liquid for the mass transfer to take part.
a) Soluble
b) Insoluble
c) Partially soluble
d) Inert

Explanation: Generally, the purpose is to add the moisture to the gas. So, the gas won’t soluble in the liquid. Due to the heat transfer, the solute gets transferred between the phases.

3. At the gas temperature, the liquid is in equilibrium with vapour for ____________
a) Saturated gas
b) Unsaturated gas
c) Partially saturated gas
d) None of the mentioned

Explanation: The name saturated means the net mass transfer between the phases is equal which means the system is at equilibrium.

4. In an operation, the enthalpy is similar throughout the initial and final condition such operation is
c) Isothermal
d) Non-isothermal

Explanation: For an adiabatic condition, there won’t be any heat addition or removal. So the enthalpy remains the same.

5. For an air(A)-water vapour(B) mixture, the partial pressure of the air is 5 pa and the total pressure of the system is 15 pa. The absolute humidity in mass of air/mass of water vapour is
a) 0.805
b) 0.311
c) 0.705
d) 0.411

Explanation: Absolute humidity = 5/ (10-5) x (29/18) = 0.805.
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6. Mass absolute humidity is
a) Absolute humidity
b) Grosvenor humidity
c) Relative humidity
d) All of the mentioned

Explanation: Grosvenor proved the absolute humidity in terms of mass absolute humidity.

7. By differencing the temperature, heat added or removed is
a) Sensible heat
b) Latent heat
c) Heat of vaporization
d) None of the mentioned

Explanation: Heat gain or loss is known as sensible heat.

8. For an air(A)-water vapour(B) mixture, the partial pressure of the air is 5 pa and the total pressure of the system is 15 pa. The molal absolute humidity is
a) 0.5
b) 1
c) 1.5
d) 2

Explanation: Pressure of A/Total pressure- Pressure of A = 5/10 =0.5.

9. The humidity is represented in
a) Humidity chart
b) Psychometric chart
c) Psychometric chart or humidity chart
d) All of the mentioned

Explanation: The chart where dry bulb and wet bulb temperature are interlinked is a humidity chart or psychometric chart.

10. De-humidification is done in
d) None of the mentioned

Explanation: For de-humidification, there should be no heat addition or heat removal. For that, the adiabatic saturation temperature is maintained.

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