250+ TOP MCQs on Degrees of Freedom Analysis in Steady-State Process and Answers

tough Chemical Engineering Questions on “Degrees of Freedom Analysis in Steady-State Process”.

1. What is the work of drying process?
a) Decreases the moisture content
b) Vaporizes water
c) Increases the moisture content
d) None of the mentioned

Answer: a
Clarification: Drying decreases the moisture content of air.

2. What is the work of the humidification process?
a) Vaporization
b) Freezing
c) Condensing
d) None of the mentioned

Answer: a
Clarification: Humidification vaporizes liquid water to moist air.

3. In condensation, moist air is cooled below its which temperature?
a) Dew-point temperature
b) Dry-bulb temperature
c) Wet-bulb temperature
d) Saturation temperature

Answer: d
Clarification: In condensation, moist air is cooled below its saturation temperature.

4. What is added to the moist air in the combustion process?
a) Water
b) Carbon dioxide
c) Oxygen
d) None of the mentioned

Answer: a
Clarification: Water is added to the moist air in the combustion process.

5. In air conditioning process, what has to be done first to the moist air?
a) Heating
b) Cooling
c) Heating & Cooling
d) None of mentioned

Answer: a
Clarification: In air conditioning process, moist air is heated and then cooled.

6. Enthalpy of air is 15 J and enthalpy of water vapor is 20 J, if the total enthalpy of the system is 20 J, what is the humidity of the system?
a) 25%
b) 50%
c) 75%
d) 100%

Answer: a
Clarification: 20 = 15 + 20*H, => H = 0.25 = 25%.

7. Enthalpy of air is 5 J and enthalpy of water vapor is 10 J, if the total enthalpy of the system is 25 J, what is the humidity of the system?
a) 50%
b) 100%
c) 150%
d) 200%

Answer: d
Clarification: 25 = 5 + 10*H, => H = 2, => H = 200%.

8. Enthalpy of air is 10 J and enthalpy of water vapor is 15 J, if the total enthalpy of the system is 25 J, what is the humidity of the system?
a) 20%
b) 50%
c) 100%
d) 180%

Answer: c
Clarification: 25 = 10 + 15*H, => H = 1, => H = 100%.

9. Enthalpy of air is 15 J and enthalpy of water vapor is 20 J, if the total enthalpy of the system is 25 J, what is the humidity of the system?
a) 10%
b) 50%
c) 100%
d) 200%

Answer: b
Clarification: 25 = 15 + 20*H, => H = 0.5, => H = 50%.

10. Enthalpy of air is 20 J and enthalpy of water vapor is 6 J, if the total enthalpy of the system is 23 J, what is the humidity of the system?
a) 10%
b) 20%
c) 40%
d) 50%

Answer: d
Clarification: 23 = 20 + 6*H, => H = 0.5, => H = 50%.

11. The humidity at dry-bulb temperature of 20^oC is 40% and the humidity at dry-bulb temperature of 25^oC is 25%, what is the slope of adiabatic cooling line?
a) 0.03
b) -0.03
c) 0.05
d) -0.05

Answer: b
Clarification: Slope of adiabatic cooling line = (0.4 – 0.25)/(20 – 25) = -0.03.

12. The humidity at dry-bulb temperature of 23^oC is 30% and the humidity at dry-bulb temperature of 28^oC is 25%, what is the slope of adiabatic cooling line?
a) -0.01
b) -0.02
c) -0.03
d) -0.05

Answer: a
Clarification: Slope of adiabatic cooling line = (0.3 – 0.25)/(23 – 28) = -0.01.

13. The humidity at dry-bulb temperature of 20^oC is 30% and the humidity at dry-bulb temperature of 22^oC is 24%, what is the slope of adiabatic cooling line?
a) -0.01
b) -0.02
c) -0.03
d) -0.05

Answer: c
Clarification: Slope of adiabatic cooling line = (0.3 – 0.24)/(20 – 22) = -0.03.

14. The humidity at dry-bulb temperature of 20^oC is 10% and the humidity at dry-bulb temperature of 23^oC is 4%, what is the slope of adiabatic cooling line?
a) -0.01
b) -0.02
c) -0.03
d) -0.05

Answer: b
Clarification: Slope of adiabatic cooling line = (0.1 – 0.04)/(20 – 23) = -0.02.

15. The humidity at dry-bulb temperature of 20^oC is 12% and the humidity at dry-bulb temperature of 23^oC is 3%, what is the slope of adiabatic cooling line?
a) -0.01
b) -0.02
c) -0.03
d) -0.05

Answer: c
Clarification: Slope of adiabatic cooling line = (0.12 – 0.03)/(20 – 23) = -0.03.