This set of Mass Transfer Assessment Questions focuses on “Diffusivity At 25 Degree Celsius And 1 atm Pressure”.
1. What is the value of diffusivity for ammonia?
a) 0.26
b) 0.27
c) 0.28
d) 0.29
View Answer
Explanation: Ammonia is a colorless gas and it boils at a pressure of one atmosphere. It is easily liquefied due to the strong hydrogen bonding. Its unit is cm2/s.
2. Which one is having the highest value of diffusivity?
a) Hydrogen
b) Oxygen
c) Water
d) Methanol
View Answer
Explanation: Thermal diffusivity of hydrogen is 0.410 while that of oxygen, water and methanol are 0.206, 0.259 and .0159 respectively. Its unit is cm 2/s.
3. What is the value of diffusivity for hydrogen?
a) 0.210
b) 0.310
c) 0.410
d) 0.510
View Answer
Explanation: It is highly flammable and will burn in air at a very wide range of concentrations. It reacts with every oxidizing agent. Its unit is cm 2/s.
4. Which one is having the lowest value of diffusivity?
a) Acetic acid
b) Oxygen
c) Benzene
d) Toluene
View Answer
Explanation: Thermal diffusivity of toluene is 0.084 while that of acetic acid, oxygen and benzene are 0.133, 0.206 and 0.081 respectively. Its unit is cm 2/s.
5. What is the value of diffusivity for water?
a) 0.233
b) 0.256
c) 0.276
d) 0.298
View Answer
Explanation: It is transparent in the visible electromagnetic spectrum. It has high specific heat capacity and latent heat of vaporisation. Its unit is cm 2/s.
6. Which one is having the highest value of diffusivity?
a) Water
b) Oxygen
c) Hydrogen
d) Carbon dioxide
View Answer
Explanation: Thermal diffusivity of water is 0.256 while that of oxygen, hydrogen and carbon dioxide are 0.206, 0.210 and 0.164 respectively. Its unit is cm2/s.
7. What is the value of diffusivity for ethyl alcohol?
a) 0.117
b) 0.118
c) 0.119
d) 0.120
View Answer
Explanation: There are extensive hydrogen bonding between its molecules. Its unit is cm2/s.
8. Which one is having the lowest value of diffusivity?
a) Glucose
b) Urea
c) Ethanol
d) Oxygen
View Answer
Explanation: Thermal diffusivity of glucose is 0.60 while that of urea, oxygen and ethanol are 8.06, 1.80 and 1.00 respectively. Its unit is cm2 /s.
9. What is the value of diffusivity for benzene?
a) 0.055
b) 0.066
c) 0.077
d) 0.088
View Answer
Explanation: It is having higher diffusivity so they diffuse faster into each other. Its unit is cm2/s.
10. Which one is having the highest value of diffusivity?
a) Ammonia
b) Urea
c) Glucose
d) Ethanol
View Answer
Explanation: Thermal diffusivity of urea is 8.06 while that of ammonia, glucose and ethanol are 1.76, 0.60 and 1.00 respectively. Its unit is cm 2/s.
Sanfoundry Global Education & Learning Series – Mass Transfer.
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