RETA CARO Test 1 Exam – Questions with
Answers and Rationales (Latest Update
2026/2027)
1. What does temperature indicate?
A. Total heat energy in an object
B. Intensity of heat energy in an object
C. Latent heat of fusion
D. Specific heat capacity
✔ Correct Answer: B
Rationale: Temperature measures the average kinetic energy (intensity) of
molecules, not the total heat.
2. What is required to move heat from one object to another?
A. Equal temperatures
B. Temperature difference
C. Same mass
D. Identical materials
✔ Correct Answer: B
Rationale: Heat flows naturally from warmer to cooler objects only when a
temperature difference exists.
3. Which of these is required to obtain a valid reading from a pressure-temperature
chart?
A. The refrigerant must be superheated
B. The refrigerant must be in a saturated condition
C. The refrigerant must be subcooled
D. The refrigerant must be a gas only
,✔ Correct Answer: B
Rationale: Pressure-temperature charts apply only when liquid and vapor coexist
(saturated state).
4. Which of these is an essential component of a mechanical refrigeration system?
A. Oil separator
B. Expansion device
C. Hot gas bypass
D. Accumulator
✔ Correct Answer: B
Rationale: The expansion device meters refrigerant into the evaporator and creates
a pressure drop – essential for all mechanical systems.
5. What is a function of a compressor in a mechanical refrigeration system?
A. To cool the refrigerant
B. To evaporate the refrigerant
C. To accept vapor from the evaporator and compress it to increase its
pressure and temperature
D. To subcool the liquid
✔ Correct Answer: C
Rationale: The compressor raises refrigerant pressure and temperature so it can
reject heat in the condenser.
6. Which of these accurately describes subcooled liquid?
A. Liquid cooled below atmospheric pressure
B. Liquid cooled below its saturation temperature at the existing pressure
C. Liquid at its boiling point
D. Liquid mixed with vapor
✔ Correct Answer: B
Rationale: Subcooling means the liquid temperature is lower than the saturation
temperature at that pressure.
, 7. What does the term compression ratio refer to?
A. Ratio of suction pressure to discharge pressure in PSIG
B. Ratio of discharge pressure to suction pressure in PSIA
C. Ratio of cylinder volume to clearance volume
D. Ratio of horsepower to tonnage
✔ Correct Answer: B
Rationale: Compression ratio = absolute discharge pressure ÷ absolute suction
pressure (PSIA).
8. Which refrigerant is more forgiving to moisture in the refrigeration system?
A. R-134a
B. R-22
C. R-404A
D. R-717 (Ammonia)
✔ Correct Answer: D
Rationale: Ammonia is miscible with water and does not form acids or ice as
readily as halocarbons.
9. Which of these is most likely to occur when air leaks into a refrigeration
system?
A. Decrease in compressor discharge pressure
B. Increase in compressor discharge pressure
C. Decrease in condenser subcooling
D. No effect on pressures
✔ Correct Answer: B
Rationale: Non-condensable air accumulates in the condenser, raising head
pressure.
Answers and Rationales (Latest Update
2026/2027)
1. What does temperature indicate?
A. Total heat energy in an object
B. Intensity of heat energy in an object
C. Latent heat of fusion
D. Specific heat capacity
✔ Correct Answer: B
Rationale: Temperature measures the average kinetic energy (intensity) of
molecules, not the total heat.
2. What is required to move heat from one object to another?
A. Equal temperatures
B. Temperature difference
C. Same mass
D. Identical materials
✔ Correct Answer: B
Rationale: Heat flows naturally from warmer to cooler objects only when a
temperature difference exists.
3. Which of these is required to obtain a valid reading from a pressure-temperature
chart?
A. The refrigerant must be superheated
B. The refrigerant must be in a saturated condition
C. The refrigerant must be subcooled
D. The refrigerant must be a gas only
,✔ Correct Answer: B
Rationale: Pressure-temperature charts apply only when liquid and vapor coexist
(saturated state).
4. Which of these is an essential component of a mechanical refrigeration system?
A. Oil separator
B. Expansion device
C. Hot gas bypass
D. Accumulator
✔ Correct Answer: B
Rationale: The expansion device meters refrigerant into the evaporator and creates
a pressure drop – essential for all mechanical systems.
5. What is a function of a compressor in a mechanical refrigeration system?
A. To cool the refrigerant
B. To evaporate the refrigerant
C. To accept vapor from the evaporator and compress it to increase its
pressure and temperature
D. To subcool the liquid
✔ Correct Answer: C
Rationale: The compressor raises refrigerant pressure and temperature so it can
reject heat in the condenser.
6. Which of these accurately describes subcooled liquid?
A. Liquid cooled below atmospheric pressure
B. Liquid cooled below its saturation temperature at the existing pressure
C. Liquid at its boiling point
D. Liquid mixed with vapor
✔ Correct Answer: B
Rationale: Subcooling means the liquid temperature is lower than the saturation
temperature at that pressure.
, 7. What does the term compression ratio refer to?
A. Ratio of suction pressure to discharge pressure in PSIG
B. Ratio of discharge pressure to suction pressure in PSIA
C. Ratio of cylinder volume to clearance volume
D. Ratio of horsepower to tonnage
✔ Correct Answer: B
Rationale: Compression ratio = absolute discharge pressure ÷ absolute suction
pressure (PSIA).
8. Which refrigerant is more forgiving to moisture in the refrigeration system?
A. R-134a
B. R-22
C. R-404A
D. R-717 (Ammonia)
✔ Correct Answer: D
Rationale: Ammonia is miscible with water and does not form acids or ice as
readily as halocarbons.
9. Which of these is most likely to occur when air leaks into a refrigeration
system?
A. Decrease in compressor discharge pressure
B. Increase in compressor discharge pressure
C. Decrease in condenser subcooling
D. No effect on pressures
✔ Correct Answer: B
Rationale: Non-condensable air accumulates in the condenser, raising head
pressure.
