Question 1

Minus 459&#176;F is the temperature considered to be:&#10;A) extremely cold&#10;B) absolute 0&#10;C) absolute 459&#10;D) the lowest temperature ever obtained

Accepted Answer

Minus 459°F is extremely cold, but it is not absolute zero, which is -459.67°F. It is also not equivalent to 0K or the lowest temperature ever obtained.

Question 2

What is the term used to describe the temperature of a liquid below its boiling point?&#10;A) superheated&#10;B) evaporated&#10;C) subcooled&#10;D) frozen

Accepted Answer

The term used to describe the temperature of a liquid below its boiling point is subcooled. This means that the liquid is still in its liquid state, but its temperature is lower than that of its boiling point. The other options are not applicable: 
A) Superheated means that the temperature of a liquid is higher than its boiling point.
B) Evaporated means that the liquid has changed into a gas by reaching its boiling point and overcome its vapor pressure.
D) Frozen means that the temperature of a liquid has dropped to a point where it solidifies.

Question 3

The direction heat flows is from:&#10;A) high temperature to lower temperature&#10;B) low temperature to high temperature&#10;C) molecule to molecule&#10;D) atom to atom

Accepted Answer

Heat flows from high temperature to lower temperature, due to the difference in energy between the two. Heat always flows from a warmer object to a cooler object until they reach thermal equilibrium.

Question 4

A perfect vacuum is considered to be:&#10;A) 10 inches of mercury&#10;B) 15 inches of mercury&#10;C) 29 inches of mercury&#10;D) 30 inches of mercury

Accepted Answer

30 inches of mercury is the highest possible vacuum level that can be achieved, meaning that there is no air or gas present in the space being measured. The other choices are vacuum levels, but they are not considered perfect or complete vacuums.

Question 5

How much pressure would you have to apply to the surface of water in a closed container to increase the boiling point to 227&#176; F?&#10;A) 2 pounds&#10;B) 3 pounds&#10;C) 4 pounds&#10;D) 5 pounds

Accepted Answer

To increase the boiling point of water to 227° F (which is approximately 108.3° C), you would need to increase the pressure inside the container. The normal boiling point of water is 100° C at 1 atmosphere of pressure. According to the Clausius-Clapeyron relation, the boiling point of water increases by about 0.5 degrees Celsius for each additional atmosphere of pressure. To raise the boiling point by approximately 8.3° C, you would need to add roughly 16.6 additional atmospheres of pressure, since 1 atmosphere is equivalent to about 14.7 pounds per square inch (psi), this would require an increase of about 244 psi. However, the options provided suggest a misunderstanding or simplification of the concept. In a simplified context, assuming a direct and not scientifically accurate correlation, and given the options, 5 pounds of additional pressure is the closest, albeit not scientifically accurate, to the concept of increasing pressure to raise the boiling point.

Question 6

What temperature would it be if all the molecules stopped moving?&#10;A) 100&#176; F&#10;B) 32&#176;F&#10;C) 0&#176;F&#10;D) -459&#176;F

Accepted Answer

The temperature at which all the molecules stop moving is known as absolute zero. This temperature is equal to -459°F. Therefore, choice D is the correct answer. Choices A, B, and C are all above absolute zero and would still have some molecular motion.

Question 7

What kind of a gauge will read both positive and negative pressure?&#10;A) A micron gauge&#10;B) A compound gauge&#10;C) A high pressure manifold gauge&#10;D) A gauge that reads in PSIA

Accepted Answer

A compound gauge is designed to read both positive and negative pressure. It is typically used in refrigeration and air conditioning systems to measure both vacuum pressure during the evacuation process and positive pressure during normal operation. A micron gauge (A) only measures very low pressure, while a high pressure manifold gauge (C) and a gauge that reads in PSIA (D) only measure positive pressure.

Question 8

When is the largest amount of heat energy absorbed or released during the air conditioning process?&#10;A) During the freezing process&#10;B) During the evaporation process&#10;C) During the condensing process&#10;D) Both statements B and C are correct

Accepted Answer

The largest amount of heat energy is absorbed or released during the evaporation and condensing processes in air conditioning. During evaporation, a significant amount of heat is absorbed from the environment, cooling it down. Conversely, during condensation, heat is released back into the environment. Both processes are crucial for the effective transfer of heat in air conditioning systems.

Question 9

What is considered to be atmospheric pressure at sea level?&#10;A) 5 PSIG&#10;B) 10 PSIA&#10;C) 14.7 PSIG&#10;D) 14.7 PSIA

Accepted Answer

The atmospheric pressure at sea level is 14.7 pounds per square inch absolute (PSIA). This is because at sea level, the weight of the Earth's atmosphere is pressing down on the surface with a force of approximately 14.7 pounds per square inch. This pressure is measured in PSIA, which is the pressure relative to a perfect vacuum.

Question 10

Thermal equilibrium takes place when:&#10;A) The heat from an object is given off to a cooler room&#10;B) The heat of the room is transferred to a cooler object&#10;C) Heat is removed very quickly from an object in a room&#10;D) Both the object and the room are at exactly the same temperature

Accepted Answer

Thermal equilibrium occurs when two objects or systems are at the same temperature and no heat transfer occurs between them. Therefore, both the object and the room must be at exactly the same temperature for thermal equilibrium to take place.

Question 11

When the pressure of a vapor goes up:&#10;A) Its temperature an boiling point go down&#10;B) Its temperature and boiling point go up&#10;C) Its temperature goes up while its boiling point goes down&#10;D) Its temperature goes down while its boiling point goes up

Accepted Answer

The answer of When the pressure of a vapor goes...

Question 12

What type of heat transfer takes place when temperature between the source and the absorbent surface is not affected?&#10;A) conduction&#10;B) sublimation&#10;C) convection&#10;D) radiation

Accepted Answer

The answer of What type of heat transfer takes place...

Question 13

When the humidity level of the ambient air increases:&#10;A) The air conditioning system does not have to work as hard to reduce the cab temperature.&#10;B) The air conditioning system must work much harder to reduce the cab temperature.&#10;C) It has no affect on the air conditioning system because it is self contained for the ambient air.&#10;D) The air conditioning compressor runs cooler.

Accepted Answer

The answer of When the humidity level of the ambient...

Question 14

If an air conditioning system is considered to be a two ton unit, it would be capable of removing _______ BTU's of heat energy per hour.&#10;A) 1000&#10;B) 2000&#10;C) 12,000&#10;D) 24,000

Accepted Answer

The answer of If an air conditioning system is considered...

Question 15

Water in a closed container can boil at room temperature if:&#10;A) Enough pressure is removed from the surface of the water.&#10;B) Enough pressure is a applied to the surface of the water.&#10;C) Enough heat is removed from the water.&#10;D) Superheated

Accepted Answer

The answer of Water in a closed container can boil...

Deck 3: Thermodynamics