Power Engineering - 4B9 UPDATED ACTUAL Questions and CORRECT
Answers
Question: Which of the following statements is false? a. Group A3 refrigerants are low flammable b.
Group B1 refrigerants are nonflammable c. Group A1 refrigerants are nonflammable d. Group B3
refrigerants are highly toxic e. Group B2 refrigerants are highly toxic
Correct Answer: a. Group A3 refrigerants are low flammable
Question: The function of the condenser is to
Correct Answer: a. Pressurize low, pressure refrigerant vapor b. Change high, pressure refrigerant vapor to
liquid c. Lower the liquid refrigerant pressure d. Vent off vaporized refrigerant e. Vaporize the liquid
refrigerant: b. Change high, pressure refrigerant vapor to liquid
Question: It is not true that
Correct Answer: a. Group A3 refrigerants are low flammable b. Group B2 refrigerants are highly toxic c.
Group A1 refrigerants are nonflammable d. Group B3 refrigerants are highly toxic e. Group B1 refrigerants
are nonflammable: a. Group A3 refrigerants are low flammable
Question: A liquid evaporating is an example of a
Correct Answer: a. Gain of sensible heat b. Loss of latent heat c. Gain of latent heat d. Loss of sensible
heat e. No change in heat content: c. Gain of latent heat
Question: What is not true? a. Inlet temperature of the compressor is lower that the outlet temperature of
the condenser b. Refrigerant temperature in evaporator is lower that at the inlet of the compressor c. The
temperature of refrigerant on both side of the control valve is different d. Temperature of evaporator is
higher that the inlet temperature of the compressor e. Discharge temperature of the compressor is higher
that the inlet temperature of the control valve
Correct Answer: d. Temperature of evaporator is higher that the inlet temperature of the compressor
Question: Which of the following statements is true? a. After the refrigerant gives up its heat, it leaves the
condenser as a liquid b. The refrigerant vapor is compressed in the condenser c. The control valve regulates
the pressure of the compressor d. The condensed refrigerant is stored in the compressor e. Refrigerant is
admitted to the evaporator by the compressor
Correct Answer: a. After the refrigerant gives up its heat, it leaves the condenser as a liquid
Question: The refrigerant with the highest refrigerating effect per kg of any refrigerant is
Correct Answer: a. Carbon dioxide b. Butane c. Water d. Ammonia e. Propane: d. Ammonia
Question: What is the coefficient of performance for a system with a capacity of 3 tonnes and an input
power of 5 kW? a. 2.328 b. 1.945 c. 0.429 d. 0.674 e. 1.672
Correct Answer: a. 2.328
Question: The refrigerant that has no negative effect on the atmosphere is
Correct Answer: a. R22 b. R113 c. R12 d. R11 e. None of the answers: e. None of the answers
Question: Why the condenser temperature is high? 1. To balance against the evaporator 2. Due to its high
pressure 3. It is at the end of line 4. To make it possible to release heat 5. To let the refrigerant turn into
liquid a. 1, 2, 4 b. 1, 3, 5 c. 3, 4, 5 d. 2, 3, 4 e. 2, 4, 5
,Correct Answer: e. 2, 4, 5
Question: Refrigeration is transfer of heat
Correct Answer: a. From a lower temperature substance to a higher surrounding b. From any substance c.
From a higher temperature substance to a lower surrounding d. Any combination of the answers e. To any
substance: a. From a lower temperature substance to a higher surrounding
Question: A running vacuum pump connected to a refrigeration tank may
Correct Answer: 1. Lower the tank pressure 2. Raise the tank pressure 3. Have no effect on the tank
pressure 4. May raise the tank temperature 5. May lower the tank temperature a. 2, 5 b. 1, 5 c. 2, 4 d. 3, 4 e.
1, 4: b. 1, 5
Question: If a cooled medium had an evaporation temperature of 2C, the evaporation temperature of the
liquid refrigerant should be approximately
Correct Answer: a. -8C to -3C b. 2C c. 6C to 8C d. 0C e. 1C: a. -8C to -3C
Question: Which one does not contribute to the leakage tendency of a refrigerant gas? a. Its viscosity b. Its
operating pressure c. Its molecular mass d. Its miscibility e. Its density
Correct Answer: d. Its miscibility
Question: Which column of the refrigeration tables lists the absolute pressure in kPa? a. Column 4 b.
Column 2 c. Column 1 d. Column 5 e. Column 3
Correct Answer: b. Column 2
Question: Standard conditions in refrigeration are referred to
Correct Answer: a. 101.3 kPa and 0C b. 14.7 psi and 0F c. None of the answers d. Evaporator temperature
at 5F and condenser at 86F e. Evaporator temperature at 0C and condenser at 15C: d. Evaporator
temperature at 5F and condenser at 86F
Question: Which of the following has the highest boiling point? a. Water b. CO2 c. Ammonia d. Propane e.
Butane
Correct Answer: a. Water
Question: Which of the following is not a requirement for an ideal refrigerant? a. A non-corrosive action
on metals b. A low boiling point c. A fairly low condensing pressure d. A non-poisonous nature e. Light in
weight
Correct Answer: e. Light in weight
Question: Which refrigerant does not damage the ozone layer? a. R-717 b. R-11 c. R-113 d. R-12 e. R-22
Correct Answer: a. R-717
Question: What is the name of the refrigerant that has the following characteristics? It is nonflammable,
odourless, nontoxic, it does not have a corrosive effect on metal if water is present and at atmospheric
pressure it has a boiling point of -40.6 degrees C. a. Propane b. Butane c. Ammonia d. Freon-22 e. Sulphur
Dioxide
Correct Answer: d. Freon-22
Question: Compression ratio is defined as the compressor cylinder _____ pressure divided by the _____
pressure. a. Gauge suction / gauge discharge b. Liquid / vapor c. Absolute discharge / absolute suction d.
, Gauge discharge / gauge suction e. Absolute suction / absolute discharge
Correct Answer: c. Absolute discharge / absolute suction
Question: In a refrigeration system
Correct Answer: 1- Flashed refrigerant into vapor in an evaporator can be as high as 30% 2- The flashed
refrigerant take part in the actual refrigerating process 3- The flashed refrigerant amount depends on the
temperature difference between the liquid refrigerant before the control 4- The net refrigerating effect of a
refrigerant must be calculated under the standard conditions a. 1, 2, 3, 4 b. 1, 2 c. 1, 3, 4 d. 2, 4 e. 1, 2, 3: c.
1, 3, 4
Question: In an ice box
Correct Answer: a. Temperature goes below 0C b. Cooler air sinks down c. Warmer air sinks down d. Ice
does not melt e. Cooler air rises: b. Cooler air sinks down
Question: Refrigeration is the process of a. Adding heat to a substance b. Lowering the temperature of a
substance below its surrounding c. All of the answers d. Removing heat from a substance e. Raising the
temperature of a substance above its surrounding
Correct Answer: b. Lowering the temperature of a substance below its surrounding
Question: Standard conditions in refrigeration are referred to
Correct Answer: a. Pressures of 15 kPa in Evaporator and 30 kPa in condenser b. Evaporator temperature
at -15C and condenser at 30C c. None of the answers d. Evaporator temperature at -30C and condenser at
15C e. 101.3 kPa and 0C: b. Evaporator temperature at -15C and condenser at 30C
Question: Which of the following is an example of a loss of latent heat? 1. Water Evaporating 2. Ice
Melting 3. Refrigerant evaporating 4. Air Cooling a. 1, 3 b. None of the answers c. 1, 3, 4 d. 4 e. 3
Correct Answer: b. None of the answers
Question: One tonne of refrigerant is
Correct Answer: a. 233 kJ per minute b. 335 J per second c. 100 kJ per minute d. 13958 kJ per day e.
13958 J per hour: a. 233 kJ per minute
Question: Why is the condenser temperature higher than the evaporator temperature? 1. To balance against
the evaporator 2. Due to its higher pressure 3. Because it is at the end of line 4. To make it possible to
release heat 5. To allow the refrigerant vapor to be condensed to liquid a. 1, 3, 5 b. 2, 4, 5 c. 3, 4, 5 d. 1, 2, 4
e. 2, 3, 4
Correct Answer: b. 2, 4, 5
Question: If you keep adding heat to a liquid and still its temperature does not change, then that heat is
called
Correct Answer: a. Wasted heat b. Warming up heat c. Latent heat d. None of the answers e. Sensible heat:
c. Latent heat
Question: The amount of heat absorbed up by a refrigerant in the evaporator is equal to
Correct Answer: a. Its latent heat of vaporization minus the heat required to flash the liquid due to the
pressure drop b. Its latent heat of fusion c. Its latent heat of fusion minus the heat required to flash the liquid
due to the pressure drop d. The difference between the head pressure and the system pressure times the
mass in kg e. Its latent heat of vaporization: a. Its latent heat of vaporization minus the heat required to flash
Answers
Question: Which of the following statements is false? a. Group A3 refrigerants are low flammable b.
Group B1 refrigerants are nonflammable c. Group A1 refrigerants are nonflammable d. Group B3
refrigerants are highly toxic e. Group B2 refrigerants are highly toxic
Correct Answer: a. Group A3 refrigerants are low flammable
Question: The function of the condenser is to
Correct Answer: a. Pressurize low, pressure refrigerant vapor b. Change high, pressure refrigerant vapor to
liquid c. Lower the liquid refrigerant pressure d. Vent off vaporized refrigerant e. Vaporize the liquid
refrigerant: b. Change high, pressure refrigerant vapor to liquid
Question: It is not true that
Correct Answer: a. Group A3 refrigerants are low flammable b. Group B2 refrigerants are highly toxic c.
Group A1 refrigerants are nonflammable d. Group B3 refrigerants are highly toxic e. Group B1 refrigerants
are nonflammable: a. Group A3 refrigerants are low flammable
Question: A liquid evaporating is an example of a
Correct Answer: a. Gain of sensible heat b. Loss of latent heat c. Gain of latent heat d. Loss of sensible
heat e. No change in heat content: c. Gain of latent heat
Question: What is not true? a. Inlet temperature of the compressor is lower that the outlet temperature of
the condenser b. Refrigerant temperature in evaporator is lower that at the inlet of the compressor c. The
temperature of refrigerant on both side of the control valve is different d. Temperature of evaporator is
higher that the inlet temperature of the compressor e. Discharge temperature of the compressor is higher
that the inlet temperature of the control valve
Correct Answer: d. Temperature of evaporator is higher that the inlet temperature of the compressor
Question: Which of the following statements is true? a. After the refrigerant gives up its heat, it leaves the
condenser as a liquid b. The refrigerant vapor is compressed in the condenser c. The control valve regulates
the pressure of the compressor d. The condensed refrigerant is stored in the compressor e. Refrigerant is
admitted to the evaporator by the compressor
Correct Answer: a. After the refrigerant gives up its heat, it leaves the condenser as a liquid
Question: The refrigerant with the highest refrigerating effect per kg of any refrigerant is
Correct Answer: a. Carbon dioxide b. Butane c. Water d. Ammonia e. Propane: d. Ammonia
Question: What is the coefficient of performance for a system with a capacity of 3 tonnes and an input
power of 5 kW? a. 2.328 b. 1.945 c. 0.429 d. 0.674 e. 1.672
Correct Answer: a. 2.328
Question: The refrigerant that has no negative effect on the atmosphere is
Correct Answer: a. R22 b. R113 c. R12 d. R11 e. None of the answers: e. None of the answers
Question: Why the condenser temperature is high? 1. To balance against the evaporator 2. Due to its high
pressure 3. It is at the end of line 4. To make it possible to release heat 5. To let the refrigerant turn into
liquid a. 1, 2, 4 b. 1, 3, 5 c. 3, 4, 5 d. 2, 3, 4 e. 2, 4, 5
,Correct Answer: e. 2, 4, 5
Question: Refrigeration is transfer of heat
Correct Answer: a. From a lower temperature substance to a higher surrounding b. From any substance c.
From a higher temperature substance to a lower surrounding d. Any combination of the answers e. To any
substance: a. From a lower temperature substance to a higher surrounding
Question: A running vacuum pump connected to a refrigeration tank may
Correct Answer: 1. Lower the tank pressure 2. Raise the tank pressure 3. Have no effect on the tank
pressure 4. May raise the tank temperature 5. May lower the tank temperature a. 2, 5 b. 1, 5 c. 2, 4 d. 3, 4 e.
1, 4: b. 1, 5
Question: If a cooled medium had an evaporation temperature of 2C, the evaporation temperature of the
liquid refrigerant should be approximately
Correct Answer: a. -8C to -3C b. 2C c. 6C to 8C d. 0C e. 1C: a. -8C to -3C
Question: Which one does not contribute to the leakage tendency of a refrigerant gas? a. Its viscosity b. Its
operating pressure c. Its molecular mass d. Its miscibility e. Its density
Correct Answer: d. Its miscibility
Question: Which column of the refrigeration tables lists the absolute pressure in kPa? a. Column 4 b.
Column 2 c. Column 1 d. Column 5 e. Column 3
Correct Answer: b. Column 2
Question: Standard conditions in refrigeration are referred to
Correct Answer: a. 101.3 kPa and 0C b. 14.7 psi and 0F c. None of the answers d. Evaporator temperature
at 5F and condenser at 86F e. Evaporator temperature at 0C and condenser at 15C: d. Evaporator
temperature at 5F and condenser at 86F
Question: Which of the following has the highest boiling point? a. Water b. CO2 c. Ammonia d. Propane e.
Butane
Correct Answer: a. Water
Question: Which of the following is not a requirement for an ideal refrigerant? a. A non-corrosive action
on metals b. A low boiling point c. A fairly low condensing pressure d. A non-poisonous nature e. Light in
weight
Correct Answer: e. Light in weight
Question: Which refrigerant does not damage the ozone layer? a. R-717 b. R-11 c. R-113 d. R-12 e. R-22
Correct Answer: a. R-717
Question: What is the name of the refrigerant that has the following characteristics? It is nonflammable,
odourless, nontoxic, it does not have a corrosive effect on metal if water is present and at atmospheric
pressure it has a boiling point of -40.6 degrees C. a. Propane b. Butane c. Ammonia d. Freon-22 e. Sulphur
Dioxide
Correct Answer: d. Freon-22
Question: Compression ratio is defined as the compressor cylinder _____ pressure divided by the _____
pressure. a. Gauge suction / gauge discharge b. Liquid / vapor c. Absolute discharge / absolute suction d.
, Gauge discharge / gauge suction e. Absolute suction / absolute discharge
Correct Answer: c. Absolute discharge / absolute suction
Question: In a refrigeration system
Correct Answer: 1- Flashed refrigerant into vapor in an evaporator can be as high as 30% 2- The flashed
refrigerant take part in the actual refrigerating process 3- The flashed refrigerant amount depends on the
temperature difference between the liquid refrigerant before the control 4- The net refrigerating effect of a
refrigerant must be calculated under the standard conditions a. 1, 2, 3, 4 b. 1, 2 c. 1, 3, 4 d. 2, 4 e. 1, 2, 3: c.
1, 3, 4
Question: In an ice box
Correct Answer: a. Temperature goes below 0C b. Cooler air sinks down c. Warmer air sinks down d. Ice
does not melt e. Cooler air rises: b. Cooler air sinks down
Question: Refrigeration is the process of a. Adding heat to a substance b. Lowering the temperature of a
substance below its surrounding c. All of the answers d. Removing heat from a substance e. Raising the
temperature of a substance above its surrounding
Correct Answer: b. Lowering the temperature of a substance below its surrounding
Question: Standard conditions in refrigeration are referred to
Correct Answer: a. Pressures of 15 kPa in Evaporator and 30 kPa in condenser b. Evaporator temperature
at -15C and condenser at 30C c. None of the answers d. Evaporator temperature at -30C and condenser at
15C e. 101.3 kPa and 0C: b. Evaporator temperature at -15C and condenser at 30C
Question: Which of the following is an example of a loss of latent heat? 1. Water Evaporating 2. Ice
Melting 3. Refrigerant evaporating 4. Air Cooling a. 1, 3 b. None of the answers c. 1, 3, 4 d. 4 e. 3
Correct Answer: b. None of the answers
Question: One tonne of refrigerant is
Correct Answer: a. 233 kJ per minute b. 335 J per second c. 100 kJ per minute d. 13958 kJ per day e.
13958 J per hour: a. 233 kJ per minute
Question: Why is the condenser temperature higher than the evaporator temperature? 1. To balance against
the evaporator 2. Due to its higher pressure 3. Because it is at the end of line 4. To make it possible to
release heat 5. To allow the refrigerant vapor to be condensed to liquid a. 1, 3, 5 b. 2, 4, 5 c. 3, 4, 5 d. 1, 2, 4
e. 2, 3, 4
Correct Answer: b. 2, 4, 5
Question: If you keep adding heat to a liquid and still its temperature does not change, then that heat is
called
Correct Answer: a. Wasted heat b. Warming up heat c. Latent heat d. None of the answers e. Sensible heat:
c. Latent heat
Question: The amount of heat absorbed up by a refrigerant in the evaporator is equal to
Correct Answer: a. Its latent heat of vaporization minus the heat required to flash the liquid due to the
pressure drop b. Its latent heat of fusion c. Its latent heat of fusion minus the heat required to flash the liquid
due to the pressure drop d. The difference between the head pressure and the system pressure times the
mass in kg e. Its latent heat of vaporization: a. Its latent heat of vaporization minus the heat required to flash
