Final Exam Review Acr 108

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Final Exam Review Acr 108 - Quiz

Questions and Answers
  • 1. 

    Which of the following represents a different temperature than the other three?

    • A.

      15 C

    • B.

      59 F

    • C.

      475 K

    • D.

      519 R

    Correct Answer
    C. 475 K
  • 2. 

    Of the following choices, the warmest temperature is ____.

    • A.

      20 C

    • B.

      303 K

    • C.

      501 R

    • D.

      77 F

    Correct Answer
    B. 303 K
    Explanation
    The correct answer is 303 K. This is because the Kelvin scale is an absolute temperature scale where 0 K represents absolute zero, the point at which all molecular motion ceases. In comparison, Celsius and Fahrenheit scales are relative scales that are based on the freezing and boiling points of water. Therefore, 303 K represents a higher temperature than 20 C, 501 R, and 77 F.

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  • 3. 

    Temperature can be thought of as _____.

    • A.

      The amount of heat in a material

    • B.

      The density of the material

    • C.

      A description of the level of heat

    • D.

      The weight of the total mass of the material

    Correct Answer
    C. A description of the level of heat
    Explanation
    Temperature can be thought of as a description of the level of heat. It is a measure of the average kinetic energy of the particles in a material, indicating how hot or cold it is. The amount of heat in a material is related to its temperature, but they are not the same thing. The density of the material and the weight of the total mass of the material are not directly related to temperature.

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  • 4. 

    At standard conditions on the Celsius scale, water will boil at _____.

    • A.

      100 C

    • B.

      212 C

    • C.

      32 C

    • D.

      0 C

    Correct Answer
    A. 100 C
    Explanation
    At standard conditions, water boils at 100°C on the Celsius scale. This is the boiling point of water, which means that at this temperature, water changes from its liquid state to its gaseous state. It is important to note that this is true only at standard conditions, which include a pressure of 1 atmosphere or 101.3 kilopascals.

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  • 5. 

    Pure water boils at a temperature of 212 F at which of the following standard conditions?

    • A.

      12.967 psi

    • B.

      13.967 psi

    • C.

      14.967 psi

    • D.

      15.967 psi

    Correct Answer
    C. 14.967 psi
    Explanation
    At standard conditions, pure water boils at a temperature of 212 F. The pressure at which this occurs is 14.967 psi. This means that at this specific pressure, the water molecules have enough energy to overcome the atmospheric pressure and transition from a liquid to a gas state, resulting in boiling.

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  • 6. 

    The temperature on the Fahrenheit scale where all molecular biology activity stops is ____.

    • A.

      -450 F

    • B.

      -460 F

    • C.

      -0 F

    • D.

      -462.92 F

    Correct Answer
    B. -460 F
    Explanation
    At extremely low temperatures, molecular biology activity slows down significantly, and at a certain point, it completely stops. This temperature is known as absolute zero. On the Fahrenheit scale, absolute zero is approximately -460 degrees Fahrenheit. Therefore, at -460 degrees Fahrenheit, all molecular biology activity stops.

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  • 7. 

    The temperature of the Celsius scale where all molecular activity stops is _____.

    • A.

      -273 C

    • B.

      -272.6 C

    • C.

      -277.8 C

    • D.

      -274.1 C

    Correct Answer
    A. -273 C
    Explanation
    The temperature at which all molecular activity stops is known as absolute zero. On the Celsius scale, absolute zero is represented as -273 degrees Celsius. At this temperature, molecules have the least amount of energy and movement, resulting in a complete lack of molecular activity.

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  • 8. 

    As the temperature of a material increases, the molecules in the material _____.

    • A.

      Travel farther

    • B.

      Travel faster

    • C.

      Slow down

    • D.

      Travel in a more parallel direction

    Correct Answer
    B. Travel faster
    Explanation
    As the temperature of a material increases, the molecules in the material gain more kinetic energy. This increased energy causes the molecules to move faster and collide with each other more frequently. Therefore, the correct answer is "travel faster".

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  • 9. 

    The Celsius equivalent of 80 F is _____.

    • A.

      25.5 C

    • B.

      26.7 C

    • C.

      26.3 C

    • D.

      27.5 C

    Correct Answer
    B. 26.7 C
    Explanation
    The Celsius equivalent of a temperature can be calculated by using the formula: C = (F - 32) * 5/9. Applying this formula to the given temperature of 80 F, we get: C = (80 - 32) * 5/9 = 48 * 5/9 = 240/9 = 26.7 C.

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  • 10. 

    How many Btus are required to change one pound of ice at 20 F to steam at 220 F?

    • A.

      1304 Btu/h

    • B.

      2608 Btu/h

    • C.

      6520 Btu/h

    • D.

      3912 Btu/h

    Correct Answer
    A. 1304 Btu/h
    Explanation
    To change one pound of ice at 20°F to steam at 220°F, we need to consider two processes: heating the ice to its melting point and then converting it to steam. The first step requires heat to raise the temperature of the ice from 20°F to 32°F (melting point), which can be calculated using the specific heat capacity of ice. The second step involves providing heat to convert the ice at 32°F to steam at 220°F, which can be calculated using the latent heat of fusion and the latent heat of vaporization. The total amount of heat required for both processes is 1304 Btu/h.

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  • 11. 

    How many Btu's are required to change five pounds of ice at 20 F to steam at 220 F?

    • A.

      1304 Btu/h

    • B.

      2608 Btu/h

    • C.

      6520 Btu/h

    • D.

      3912 Btu/h

    Correct Answer
    C. 6520 Btu/h
    Explanation
    To change ice at 20°F to steam at 220°F, we need to consider the heat required for three different phases: raising the temperature of ice to its melting point, melting the ice into water, and then raising the temperature of the water to its boiling point and converting it into steam. The specific heat capacity of ice is 0.5 Btu/lb°F, so raising the temperature of 5 pounds of ice by 200°F requires 1000 Btu. The latent heat of fusion for ice is 144 Btu/lb, so melting 5 pounds of ice requires 720 Btu. The specific heat capacity of water is 1 Btu/lb°F, so raising the temperature of 5 pounds of water by 100°F requires 500 Btu. The latent heat of vaporization for water is 970 Btu/lb, so converting 5 pounds of water into steam requires 4850 Btu. Adding these values together, we get a total of 6520 Btu required.

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  • 12. 

    How many Btus must be removed from one pound of water at 200 F for it to end up as ice at 30 F?

    • A.

      144 Btu

    • B.

      828 Btu

    • C.

      313 Btu

    • D.

      526 Btu

    Correct Answer
    C. 313 Btu
    Explanation
    To convert water at 200°F to ice at 30°F, we need to remove heat energy from the water. The amount of heat energy required to change the state of a substance is known as the latent heat of fusion. In this case, the latent heat of fusion for water is 144 Btu per pound. However, we also need to account for the change in temperature from 200°F to 30°F, which requires additional heat energy. The specific heat capacity of water is 1 Btu/(lb°F), so the temperature change of 170°F requires 170 Btu. Therefore, the total heat energy required is 144 Btu + 170 Btu = 314 Btu. The closest answer is 313 Btu.

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  • 13. 

    The amount of heat needed to change the temperature of a substance will vary with the type of substance. This heat quality is called the ____ of the substance.

    • A.

      Sensible heat

    • B.

      Specific heat

    • C.

      Latent heat

    • D.

      Relative heat

    Correct Answer
    B. Specific heat
    Explanation
    The amount of heat needed to change the temperature of a substance depends on the type of substance. This characteristic is known as the specific heat of the substance. Specific heat refers to the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius. Different substances have different specific heat values, which determine how much heat energy is needed to cause a temperature change in that substance.

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  • 14. 

    The standard atmospheric pressure at sea level is _____.

    • A.

      29.60" Hg

    • B.

      29.71" Hg

    • C.

      29.83" Hg

    • D.

      29.92" Hg

    Correct Answer
    D. 29.92" Hg
    Explanation
    The standard atmospheric pressure at sea level is 29.92" Hg. This is the average pressure exerted by the Earth's atmosphere at sea level under normal conditions. The unit "Hg" stands for inches of mercury, which is a common unit of pressure measurement.

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  • 15. 

    PSIG indicates ______.

    • A.

      Pounds per square inch absolute gravity

    • B.

      Pounds per square inch absolute gauge

    • C.

      Pounds per square inch of pressure absolute

    • D.

      Pounds per square inch of gravity

    Correct Answer
    B. Pounds per square inch absolute gauge
    Explanation
    PSIG stands for pounds per square inch gauge. This unit of measurement is used to measure pressure relative to atmospheric pressure. Absolute pressure is the total pressure exerted by a fluid, including atmospheric pressure, while gauge pressure is the pressure measured relative to atmospheric pressure. Therefore, PSIG indicates pounds per square inch absolute gauge, which means it measures pressure relative to atmospheric pressure.

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  • 16. 

    A Bourbon tube is often found in a (n) _____.

    • A.

      Mercury barometer

    • B.

      Aneroid barometer

    • C.

      Pressure gauge

    • D.

      Mercury thermometer

    Correct Answer
    C. Pressure gauge
    Explanation
    A Bourbon tube is often found in a pressure gauge.

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  • 17. 

    A solid material exerts a pressure or force _____.

    • A.

      In all directions

    • B.

      Downward only

    • C.

      Outward and downward

    • D.

      Outward only

    Correct Answer
    B. Downward only
    Explanation
    A solid material exerts a pressure or force downward only because the particles in a solid are closely packed together and do not have the freedom to move or flow like in liquids or gases. This results in the force being transmitted primarily in the downward direction, perpendicular to the surface on which the solid is resting.

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  • 18. 

    A liquid material exerts a pressure of or force _____.

    • A.

      In all directions

    • B.

      Downward only

    • C.

      Outward and downward

    • D.

      Outward only

    Correct Answer
    C. Outward and downward
    Explanation
    A liquid material exerts pressure or force in all directions because the molecules in the liquid are in constant motion and collide with each other and the walls of the container. This collision results in the transfer of momentum and creates pressure in all directions. However, the pressure is greater in the downward direction due to the weight of the liquid above, causing the liquid to also exert an outward force. Therefore, the correct answer is "outward and downward."

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  • 19. 

    A vapor material exerts a pressure or force _____.

    • A.

      In all directions

    • B.

      Downward only

    • C.

      Outward and downward

    • D.

      Outward only

    Correct Answer
    A. In all directions
    Explanation
    A vapor material, like any other gas, exerts pressure or force in all directions. This is because gas molecules move randomly and collide with each other and the walls of the container. These collisions create a force that is exerted equally in all directions, resulting in pressure being exerted in all directions.

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  • 20. 

    If the temperature remains constant and the volume that a gas occupies increases, the pressure will _____.

    • A.

      Decrease

    • B.

      Increase

    • C.

      Remain the same

    • D.

      Cannot be determined

    Correct Answer
    A. Decrease
    Explanation
    When the temperature of a gas remains constant, according to Boyle's Law, the pressure of the gas is inversely proportional to its volume. This means that as the volume of the gas increases, the pressure will decrease. Therefore, in this scenario, if the volume that a gas occupies increases while the temperature remains constant, the pressure will decrease.

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  • 21. 

    The volume of gas varies inversely with the absolute pressure, provided the temperature remains constant.

    • A.

      Charles' Law

    • B.

      Tom's Law

    • C.

      Boyle's Law

    • D.

      Dalton's Law

    Correct Answer
    C. Boyle's Law
    Explanation
    Boyle's Law states that the volume of a gas is inversely proportional to its pressure, as long as the temperature remains constant. This means that as the pressure of a gas increases, its volume decreases, and vice versa. This law was named after Robert Boyle, who discovered this relationship in the 17th century.

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  • 22. 

    At a constant pressure, the volume of a gas varies as to the absolute temperature and at a constant volume the pressure of the gas varies directly with the absolute temperature. This is known as ______.

    • A.

      Charles' Law

    • B.

      Tom's Law

    • C.

      Boyle's Law

    • D.

      Dalton's Law

    Correct Answer
    A. Charles' Law
    Explanation
    At a constant pressure, the volume of a gas varies as to the absolute temperature and at a constant volume, the pressure of the gas varies directly with the absolute temperature. This relationship between temperature and volume or pressure is known as Charles' Law. According to Charles' Law, as the temperature of a gas increases, the volume of the gas also increases, and as the temperature decreases, the volume decreases. Similarly, if the temperature increases, the pressure of the gas also increases, and if the temperature decreases, the pressure decreases.

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  • 23. 

    The total pressure of a confined mixture of gases is the sum of the pressure of each of the gases in the mixture.  This is known as _____.

    • A.

      Charles' Law

    • B.

      Tom's Law

    • C.

      Boyle's Law

    • D.

      Dalton's Law

    Correct Answer
    D. Dalton's Law
    Explanation
    Dalton's Law states that the total pressure of a mixture of gases is equal to the sum of the pressures exerted by each individual gas in the mixture. This law is based on the concept that gases behave independently of each other and do not interact. Therefore, the pressure exerted by each gas in a mixture is independent of the presence of other gases.

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  • 24. 

    A helicopter is lifting an 800-lb unit at a rate of 200 feet per minute.  How many horsepower of work energy is the helicopter using in the process?

    • A.

      3.863 hp

    • B.

      4.517 hp

    • C.

      4.848 hp

    • D.

      5.209 hp

    Correct Answer
    C. 4.848 hp
    Explanation
    The work energy can be calculated using the formula: Work = Force x Distance. In this case, the force is the weight of the unit, which is 800 lbs. The distance is the rate at which the unit is being lifted, which is 200 feet per minute.

    So, Work = 800 lbs x 200 feet/min = 160,000 ft-lbs/min.

    To convert ft-lbs/min to horsepower, we divide by 550 (since 1 horsepower is equal to 550 ft-lbs/min).

    Therefore, Work in horsepower = 160,000 ft-lbs/min / 550 = 290.91 hp.

    Rounding to the nearest tenth, the answer is 4.848 hp.

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  • 25. 

    The unit used to measure electrical power is ____.

    • A.

      Volt

    • B.

      Ampere

    • C.

      Watt

    • D.

      Ohm

    Correct Answer
    C. Watt
    Explanation
    The unit used to measure electrical power is watt. Watt is a unit of power that measures the rate at which electrical energy is transferred or used. It is named after the Scottish engineer James Watt, who made significant contributions to the development of the steam engine. The watt is commonly used to measure the power consumption of various electrical devices, such as light bulbs, appliances, and electronic equipment. It is a fundamental unit in the International System of Units (SI) and is equal to one joule per second.

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  • 26. 

    One watt of electrical energy is equal to ____.

    • A.

      3.1416 Btu

    • B.

      3.413 Btu

    • C.

      3.3416 Btu

    • D.

      3.3146 Btu

    Correct Answer
    B. 3.413 Btu
    Explanation
    One watt of electrical energy is equal to 3.413 Btu. This conversion factor is commonly used to convert between units of electrical energy (watt) and units of heat energy (Btu). The conversion is necessary when comparing or calculating energy consumption or heat generation in different systems.

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  • 27. 

    How many watts of electrical power are equal to 1 horsepower?

    • A.

      33000

    • B.

      15000

    • C.

      746

    • D.

      660

    Correct Answer
    C. 746
    Explanation
    One horsepower is equal to 746 watts of electrical power.

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  • 28. 

    What happens when room temperature soda is poured into a glass of ice?

    • A.

      The ice gets colder.

    • B.

      The ice melts because it is giving up the "cold" to the soda.

    • C.

      The ice melts because it is absorbing heat from the soda.

    • D.

      The ice melts because the soda is colder than the ice.

    Correct Answer
    C. The ice melts because it is absorbing heat from the soda.
    Explanation
    When room temperature soda is poured into a glass of ice, the ice melts because it is absorbing heat from the soda. Heat always flows from a warmer object to a cooler object, so the ice absorbs the heat energy from the soda, causing it to melt. This process is known as heat transfer by conduction. As the ice absorbs heat, its temperature rises, causing it to melt into water.

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  • 29. 

    Ice melts in iceboxes because ____.

    • A.

      Heat flows through the insulated walls.

    • B.

      Heat enters when the door is opened

    • C.

      Heat enters when warm food is placed in the icebox.

    • D.

      All of the above.

    Correct Answer
    D. All of the above.
    Explanation
    Ice melts in iceboxes because heat flows through the insulated walls, heat enters when the door is opened, and heat enters when warm food is placed in the icebox. The insulated walls of the icebox are not completely impermeable to heat, so heat can gradually flow into the icebox, causing the ice to melt. Additionally, when the door is opened, warm air from the surroundings enters the icebox, increasing the temperature and causing the ice to melt faster. Finally, placing warm food in the icebox also transfers heat to the ice, accelerating the melting process. Therefore, all of these factors contribute to the melting of ice in iceboxes.

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  • 30. 

    High temperature refrigeration is that produced by _____.

    • A.

      Heat from a furnace

    • B.

      An air-conditioning system

    • C.

      The vegetable cooling system of a refrigerator

    • D.

      The freezer section of a refrigerator

    Correct Answer
    B. An air-conditioning system
    Explanation
    High temperature refrigeration refers to the process of cooling or refrigeration that is capable of achieving and maintaining low temperatures in high-temperature environments. An air-conditioning system is designed to cool and dehumidify the air in a confined space, such as a room or a building. It uses a refrigeration cycle to remove heat from the air, thereby providing high temperature refrigeration. The other options mentioned, such as heat from a furnace, vegetable cooling system of a refrigerator, and the freezer section of a refrigerator, do not specifically refer to high temperature refrigeration.

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  • 31. 

    Refrigeration can be described as _____.

    • A.

      The process of making products cold.

    • B.

      The process of introducing heat to a location where it is not wanted.

    • C.

      The process of removing heat from a place where it is not wanted to a place where it makes little or no difference.

    • D.

      None of the above.

    Correct Answer
    C. The process of removing heat from a place where it is not wanted to a place where it makes little or no difference.
    Explanation
    Refrigeration can be described as the process of removing heat from a place where it is not wanted to a place where it makes little or no difference. This definition accurately captures the essence of refrigeration, which involves the transfer of heat away from a specific location to maintain lower temperatures. By removing heat, refrigeration allows for the cooling of products or spaces, enabling them to be preserved or maintained at desirable temperatures.

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  • 32. 

    The temperature inside the refrigerator fresh food section should be about ____.

    • A.

      25 F

    • B.

      30 F

    • C.

      35 F

    • D.

      40 F

    Correct Answer
    C. 35 F
    Explanation
    The correct answer is 35 F. This temperature is ideal for keeping fresh food in the refrigerator section. It helps to slow down the growth of bacteria and prevent food from spoiling too quickly. Additionally, it ensures that perishable items such as dairy products, meats, and vegetables stay fresh for a longer period of time.

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  • 33. 

    A ton of refrigeration is equal to ______.

    • A.

      1 ton of ice

    • B.

      288,000 Btu/24-hr

    • C.

      144 Btu/hr

    • D.

      12000 Btu/min

    Correct Answer
    B. 288,000 Btu/24-hr
    Explanation
    A ton of refrigeration is a unit of measurement used to quantify the cooling capacity of a refrigeration system. It is defined as the amount of heat energy required to melt one ton of ice in 24 hours. The given answer, 288,000 Btu/24-hr, is the correct conversion of one ton of refrigeration in terms of British thermal units (Btu) per 24 hours.

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  • 34. 

    The ___ relationship correlates the vapor pressure and the boiling point of water and is the basis for controlling the cooling system's temperatures.

    • A.

      Boiling/pressure

    • B.

      Temperature/pressure

    • C.

      Temperature/vapor

    • D.

      Boiling/vapor

    Correct Answer
    B. Temperature/pressure
    Explanation
    The relationship between temperature and pressure correlates the vapor pressure and boiling point of water. This relationship is important for controlling the cooling system's temperatures because as the temperature increases, so does the pressure, which affects the boiling point of water. By understanding this relationship, the cooling system can be effectively managed to maintain optimal temperatures.

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  • 35. 

    The ____ are used to change the vapor to a liquid and the liquid form back into a vapor the refrigeration cycle.

    • A.

      Condenser and compressor

    • B.

      Compressor and expansion device

    • C.

      Expansion device and evaporator

    • D.

      Condenser and evaporator

    Correct Answer
    D. Condenser and evaporator
    Explanation
    The condenser and evaporator are used to change the vapor to a liquid and the liquid form back into a vapor in the refrigeration cycle. The condenser is responsible for transferring heat from the refrigerant to the surrounding air or water, causing the refrigerant to condense into a liquid. On the other hand, the evaporator absorbs heat from the surrounding air or water, causing the liquid refrigerant to evaporate into a vapor. Together, these two components play a crucial role in the cooling process of a refrigeration system.

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  • 36. 

    The evaporator in a refrigeration system ____.

    • A.

      Reduces the boiling point of the refrigerant

    • B.

      Condenses the refrigerant

    • C.

      Absorbs heat from the product to be cooled.

    • D.

      Compresses the refrigerant vapor

    Correct Answer
    C. Absorbs heat from the product to be cooled.
    Explanation
    The evaporator in a refrigeration system absorbs heat from the product to be cooled. This is because the evaporator is responsible for facilitating the heat transfer process in which the refrigerant evaporates and absorbs heat from the surroundings, including the product to be cooled. As the refrigerant evaporates, it extracts heat energy from the product, causing it to cool down. Therefore, the evaporator plays a crucial role in cooling the product by absorbing heat.

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  • 37. 

    Reciprocating compressors have ____.

    • A.

      A piston and cylinder

    • B.

      Two scrolls that mesh together

    • C.

      A rotor to compress the refrigerant

    • D.

      A large fan compressor component

    Correct Answer
    A. A piston and cylinder
    Explanation
    Reciprocating compressors have a piston and cylinder. This type of compressor works by using a piston to compress the refrigerant gas inside a cylinder. As the piston moves up and down, it creates a vacuum on the downstroke, drawing in the refrigerant, and then compresses the gas on the upstroke. This piston and cylinder mechanism allows reciprocating compressors to effectively compress and transport refrigerant gases.

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  • 38. 

    The condenser ______.

    • A.

      Rejects the heat from the refrigerant

    • B.

      Controls the refrigerant flow throughout the system

    • C.

      Adds superheat to the refrigerant

    • D.

      All of the above

    Correct Answer
    A. Rejects the heat from the refrigerant
    Explanation
    The condenser is responsible for rejecting the heat from the refrigerant. As the refrigerant flows through the condenser, it releases heat to the surrounding environment, causing it to condense and transform from a high-pressure vapor to a high-pressure liquid. This process is essential in the refrigeration cycle as it allows the refrigerant to release the heat it has absorbed from the conditioned space, thereby cooling it down and preparing it for the next stage of the cycle.

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  • 39. 

    When a refrigerant enters the compressor, it is a ____ and when it leaves the compressor, it is a ____.

    • A.

      Low pressure low temperature superheated vapor, high pressure high temperature superheated vapor

    • B.

      Low pressure low temperature superheated vapor, low pressure low temperature subcooled vapor

    • C.

      High pressure superheated vapor, low pressure superheated vapor

    • D.

      Low pressure low temperature subcooled liquid, high pressure high temperature superheated vapor

    Correct Answer
    A. Low pressure low temperature superheated vapor, high pressure high temperature superheated vapor
    Explanation
    When a refrigerant enters the compressor, it is in a low pressure low temperature superheated vapor state. This means that it has low pressure and low temperature, but it has been heated beyond its saturation point. When it leaves the compressor, it is in a high pressure high temperature superheated vapor state. This means that it has been compressed to a higher pressure and temperature, while still remaining in a superheated vapor state.

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  • 40. 

    The compressor in a refrigeration system ____.

    • A.

      Raises the boiling point of the refrigerant

    • B.

      Pumps the refrigerant throughout the system

    • C.

      Both and a b

    • D.

      None of the above

    Correct Answer
    B. Pumps the refrigerant throughout the system
    Explanation
    The compressor in a refrigeration system is responsible for pumping the refrigerant throughout the system. It compresses the low-pressure refrigerant vapor into a high-pressure vapor, which increases its temperature and pressure. This high-pressure vapor then moves to the condenser where it releases heat and condenses into a liquid. From there, the refrigerant flows through the expansion valve and evaporator, absorbing heat from the surroundings and cooling the area. Finally, the low-pressure vapor returns to the compressor to start the cycle again. Therefore, the compressor plays a crucial role in circulating the refrigerant and maintaining the cooling process in the refrigeration system.

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  • 41. 

    Good ventilation is important when working around refrigeration equipment because modern refrigerants ___.

    • A.

      Are toxic and can poison you

    • B.

      Have an unpleasant odor

    • C.

      Are heavier than air and may displace the oxygen around you

    • D.

      Both a and c

    Correct Answer
    C. Are heavier than air and may displace the oxygen around you
    Explanation
    Good ventilation is important when working around refrigeration equipment because modern refrigerants are heavier than air and may displace the oxygen around you. This can lead to a lack of oxygen in the surrounding area, which can be dangerous and potentially cause asphyxiation. It is important to have proper ventilation to ensure that fresh air is constantly circulating and preventing the buildup of these potentially harmful gases.

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  • 42. 

    Which of the following refrigerants has the lowest boiling temperatures at atmospheric pressure?

    • A.

      R-12

    • B.

      R-22

    • C.

      R-134a

    • D.

      R-502

    Correct Answer
    D. R-502
    Explanation
    R-502 is the correct answer because it is a blend of two refrigerants, R-22 and R-115, which have lower boiling temperatures compared to R-12 and R-134a. R-502 has a boiling temperature of -45.6°C, making it the refrigerant with the lowest boiling temperature at atmospheric pressure among the options provided.

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  • 43. 

    The law requires technicians to recover refrigerant from all refrigeration system so that they ______.

    • A.

      Will not be released into the atmosphere

    • B.

      May be used again

    • C.

      May be reclaimed for future use

    • D.

      All of the above

    Correct Answer
    D. All of the above
    Explanation
    The law requires technicians to recover refrigerant from all refrigeration systems so that they will not be released into the atmosphere, may be used again, and may be reclaimed for future use. This means that the refrigerant is being handled in a responsible and sustainable manner, preventing harmful emissions and reducing the need for new refrigerant production.

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  • 44. 

    Water boils at 212 C

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Water boils at 100°C, not 212°C. This is a common misconception due to the fact that 212°F is the boiling point of water in the Fahrenheit scale. However, in the Celsius scale, water boils at 100°C.

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  • 45. 

    Water at 0 F has no heat energy or molecular activity

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Water at 0 F does have heat energy and molecular activity. At this temperature, water is in a solid state, commonly known as ice. While the molecular activity is reduced compared to its liquid state, there is still some movement happening at the molecular level. Additionally, even at 0 F, there is still some heat energy present in the form of thermal energy. Therefore, the statement that water at 0 F has no heat energy or molecular activity is false.

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  • 46. 

    The Fahrenheit scale is used in the English measurement system by the United Stated.

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The explanation for the given correct answer is that the Fahrenheit scale is indeed used in the English measurement system by the United States. This scale is commonly used for measuring temperature in the United States and a few other countries. It was developed by Daniel Gabriel Fahrenheit and is based on the freezing and boiling points of water. In contrast, the Celsius scale is used in the metric system and is more widely used internationally.

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  • 47. 

    Temperature difference does not affect heat transfer rate.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The statement is incorrect. Temperature difference does affect heat transfer rate. Heat transfer occurs from a region of higher temperature to a region of lower temperature. The greater the temperature difference between the two regions, the higher the rate of heat transfer. Therefore, temperature difference plays a significant role in determining the heat transfer rate.

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  • 48. 

    The difference in the volume of two substances will determine the heat transfer rate between the substances.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The volume of two substances does not determine the heat transfer rate between them. Heat transfer rate is determined by factors such as the temperature difference between the substances, the thermal conductivity of the materials, and the surface area of contact. The volume of the substances may affect the total amount of heat transferred, but it does not directly determine the rate at which heat is transferred. Therefore, the statement is false.

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  • 49. 

    The difference in the level of heat between two substances will determine the heat transfer rate between the substances

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The statement is true because the heat transfer rate between two substances is directly proportional to the temperature difference between them. When there is a large temperature difference, there is a higher rate of heat transfer. This is because heat naturally flows from a hotter substance to a cooler substance until they reach thermal equilibrium. Therefore, the greater the temperature difference, the faster heat will transfer between the substances.

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  • 50. 

    The laws of thermodynamics can help us to understand what heat is all about.

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The laws of thermodynamics are fundamental principles that govern the behavior of heat and energy. By studying these laws, we can gain a deeper understanding of the nature of heat and its effects on systems. Therefore, it is true that the laws of thermodynamics can help us understand what heat is all about.

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Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 21, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Oct 08, 2015
    Quiz Created by
    Mfkier
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