This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on “Drying Operation”.
1. Moisture removal from a material/ compound is known as drying.
a) True
b) False
View Answer
Explanation: Drying is the moisture removal process from materials.
2. Find the representation X.
a) Water
b) Water vapour
c) Ice
d) All of the mentioned
View Answer
Explanation: During drying operation, the moisture content in the solid gets evaporated in the form of water vapour.
3. The solution can be dried by spraying droplets in a cold gas.
a) True
b) False
View Answer
Explanation: The moisture in the liquid solution can be removed by spraying the solution droplets in warm/ hot gas.
4. On spraying the liquid over gas leads to ____________
a) Humidification
b) Evaporation
c) Heating of gas
d) None of the mentioned
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Explanation: When we spray a liquid over gas it results in evaporation.
5. The removal of acetone from acetone-benzene mixture is drying
a) True
b) False
View Answer
Explanation: Distillation is the only process we can separate to liquid depends on its volatility.
6. The additional operation requires for drying gas and liquid is _________
a) Absorption
b) Adsorption
c) Humidification
d) De-humidification
View Answer
Explanation: Drying includes a transfer of solute in the form of water so it requires absorption.
7. The given solid will gain or remove moisture till.
a) pA > P
b) pA< P
c) pA= p
d) pA= 0
View Answer
Explanation: The operation of heat exchange and solute exchange occurs till the equilibrium occurs ( pA=P).
8. The moisture in the solid after attaining equilibrium is known as
a) Bound moisture
b) Unbound moisture
c) Equilibrium moisture
d) Free moisture
View Answer
Explanation: Once the equilibrium attain the remaining moisture in solid is because of pA < P of solid so moisture is known as equilibrium moisture content.
9. Find the equilibrium moisture content.
a) 0.2
b) 0.42
c) 0.5
d) None of the mentioned
View Answer
Explanation: At 100% saturation we get equilibrium moisture content so the value is 0.4.
10. The hysteresis of drying is due to humidification and dehumidification.
a) True
b) False
View Answer
Explanation: Hysteresis is due to absorption and desorption because these are the operation requires during dying.
11. Find the process of drying in the closed vessel given below.
a) Continuous
b) Batch
c) Semi batch
d) None of the mentioned
View Answer
Explanation: Here the closed vessel is used so the gas is allowed to contact with solid for some time and removed so it is a batch process.
12. The moisture inside the substance is known as __________
a) Bound moisture
b) Unbound moisture
c) Equilibrium moisture
d) Free moisture
View Answer
Explanation: After the surface drying i.e. removal of unbound moisture then the inside moisture starts to remove such moisture are known as bound moisture.
13. Find the weight of the wet solid if dry solid is 2 kg and the moisture is 0.5 kg.
a) 2 kg
b) 2.5kg
c) 3 kg
d) 3.5 kg
View Answer
Explanation: Wet solid= dry solid+ moisture = 2+0.5= 2.5 kg.
14. Find the moisture content in dry basis if the weight of dry solid is 5 kg and the moisture is 2 kg.
a) 0.2
b) 0.3
c) 0.4
d) 0.5
View Answer
Explanation: As it is a dry basis, the moisture content = 2/5 =0.4.
15. Find the moisture content in wet basis is the weight of the dry solid is 3 kg and the weight of the moisture is 2 kg.
a) 0.2
b) 0.3
c) 0.35
d) 0.4
View Answer
Explanation: Weight of the solid = weight of moisture/ weight of moisture + dry solid = 2/5 = 0.4.
Sanfoundry Global Education & Learning Series – Mass Transfer.
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