1.
Which of the following is true about the optimum effective temperature for human
comfort?
a) Same in winter and summer
b) Not dependent on season
c) Lower in winter than in summer
d) Higher in winter than in summer
View Answer
Answer: c
Explanation: Optimum effective temperature is dependent on climatic and seasonal
changes. So, for human comfort, the optimum effective temperature is lower in winter
than in summer.
2. The heat production from a normal healthy man when asleep is about _________
a) 50 W
b) 40 W
c) 70 W
d) 60 W
View Answer
Answer: d
Explanation: A normal healthy man when asleep produces heat nearly equal to 60 W.
This might vary depending on various parameters.
3. When the heat stored in the body is ________ the human body feels comfortable.
a) zero
b) infinite
c) positive
d) negative
View Answer
Answer: a
Explanation: The human body feels comfortable when the heat stored in the body is
zero. This is the desired comfort condition.
4. Which of the following does not mainly a factor of dependency for the degree of
warmth or cold?
a) Relative humidity
b) WBT
c) Air velocity
d) DBT
View Answer
Answer: d
Explanation: The degree of warmth or cold felt by the human body depends mainly on
dry bulb temperature, air velocity and relative humidity.
5. The effective temperature increases with a decrease in relative humidity at the same
DBT.
a) True
b) False
View Answer
Answer: b
Explanation: At the same value of dry bulb temperature, the effective temperature
decreases with a decrease in relative humidity to achieve desired comfort conditions.
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
View Answer
Answer: c
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
View Answer
Answer: b
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
View Answer
Answer: a
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
a) Adiabatic
b) Non-adiabatic
c) Isothermal
d) Non-isothermal
View Answer
Answer: a
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
View Answer
Answer: a
Explanation: Absolute humidity = 5/ (10-5) x (29/18) = 0.805.
6. Mass absolute humidity is
a) Absolute humidity
b) Grosvenor humidity
c) Relative humidity
d) All of the mentioned
View Answer
Answer: b
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
View Answer
Answer: a
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
View Answer
Answer: a
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
View Answer
Answer: d
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
a) Adiabatic temperature
b) Adiabatic saturated temperature
c) Adiabatic unsaturated temperature
d) None of the mentioned
View Answer
Answer: b
Explanation: For de-humidification, there should be no heat addition or heat removal.
For that, the adiabatic saturation temperature is maintained.
1. What is humidification?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.
View Answer
Answer: a
Explanation: For increasing the humidity of the air humidifier is used and the process is
humidification.
2. What is dehumidification?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.
View Answer
Answer: b
Explanation: Dehumidification has its use in air conditioning.
3. What is water-cooling?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.
View Answer
Answer: d
Explanation: Water cooling is used to cool down the warm water before it can be
resued.
4. What is gas cooling?
a) The process of increasing the moisture of the air is called as humidification.
b) The hot air when cooled with contact in water.
c) The warm air taken out when brought in contact with water
d) The air-water cooling done to cool down the warm water.
View Answer
Answer: c
Explanation: For cooling hot air stream water can be used. However contents may
change thereafter.
5. What is dry-bulb temperature?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a
manner that sensible heat transferred from air to liquid is equal to latent heat required
for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at
same temperature.
d) Direct measure of moisture content in a gas
View Answer
Answer: a
Explanation: It is the true temperature of air i.e not in contact with any vapor.
6. What is wet-bulb temperature?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a
manner that sensible heat transferred from air to liquid is equal to latent heat required
for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at
same temperature.
d) Direct measure of moisture content in a gas
View Answer
Answer: b
Explanation: The wet bulb temperature is measured by passing air over the bulb
covered with wet cloth.
7. What is absolute humidity?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a
manner that sensible heat transferred from air to liquid is equal to latent heat required
for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at
same temperature.
d) Direct measure of moisture content in a gas
View Answer
Answer: d
Explanation: The mass of water vapor per unit mass of gas is called absolute humidity.
8. What is relative humidity?
a) Temperature of air measured by thermometer whose bulb is dry.
b) It is the temperature attained by small amount of evaporating water in such a
manner that sensible heat transferred from air to liquid is equal to latent heat required
for evaporation.
c) The ratio of partial pressure of water vapor in air to the vapor pressure of water at
same temperature.
d) Direct measure of moisture content in a gas
View Answer
Answer: c
Explanation: The ratio of partial pressure of water vapor in air to the vapor pressure of
water at same temperature is called relative humidity.
9. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.3
a) 6666.67
b) 10000
c) 5000
d) 4000
View Answer
Answer: a
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients= 6666.67.
10. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.5
a) 6666.67
b) 10000
c) 5000
d) 4000
View Answer
Answer: d
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients=4000.
11. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.2
a) 6666.67
b) 10000
c) 5000
d) 4000
View Answer
Answer: b
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients= 10000.
12. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.4
a) 6666.67
b) 10000
c) 5000
d) 4000
View Answer
Answer: c
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients= 5000.
13. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=100
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.2
a) 2000
b) 3000
c) 1000
d) 500
View Answer
Answer: a
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients= 2000.
14. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=1000
Difference in saturation humidity and humidity of ambient air= 3
Ratio of heat and mass transfer coefficient is 0.1
a) 2000
b) 3000
c) 1000
d) 500
View Answer
Answer: b
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients= 3000.
15. What is the depression in wet-bulb temperature if
Latent heat of vaporization(l)=100
Difference in saturation humidity and humidity of ambient air= 2
Ratio of heat and mass transfer coefficient is 0.4
a) 2000
b) 3000
c) 1000
d) 500
View Answer
Answer: d
Explanation: Depression in wet bulb temperature is = l*(Difference in saturated and
humidity of ambient air)/Ratio of heat and mass transfer coefficients= 500.
