Unit 7

The point at which water or another substance may exist simultaneously as a solid, liquid, and gas is:

Triple point

The amount of space occupied by matter defines:

Volume

The substance used to compare the specific gravity of liquids is:

Water

The substance that is used as the constant common material to measure specific gravity of solids is:

Water at standard conditions

Density is defined as:

Weight divided by volume

A container is half full of liquid. If the temperature of the liquid is increased, the liquid volume:

Will increase and the empty space remaining in the container will decrease

Mass measures

how much matter exists in an object

The state of matter depends upon:

its temperature and pressure

According to the law of conservation, when matter changes state, its __________ remains the same

mass

The law of conservation of matter states that:

matter cannot be created nor destroyed

Protons have a _______ charge.

positive

Atoms are composed of:

protons, neutrons, electrons

A molecule is:

the smallest part of a substance that is not an element

Because liquids are non-compressible:

their volumes will not change when pressures change

If a material or substance in the state of a liquid or solid has a specific gravity less than ______ it will float

1.0

The temperature of the water formed by melting ice is:

32 degrees Fahrenheit

The definition of a sublimation is:

A substance in a solid state changes into the gaseous state without going through the liquid state

The wet bulb temperature for AHRI rating condition "A" is: A. 68 degrees Fahrenheit B. 70 degrees Fahrenheit C. 78 degrees Fahrenheit D. 75 degrees Fahrenheit

A. 68 degrees Fahrenheit

What is the AHRI "A" performance testing condition for air cooled by air conditioning equipment? A. 95 degrees Fahrenheit outside ambient, 80 degrees indoor dry bulb, 68 degrees Fahrenheit wet bulb B. 90 degrees Fahrenheit outside ambient, 85 degrees indoor dry bulb, 70 degrees Fahrenheit wet bulb C. 95 degrees Fahrenheit outside ambient, 75 degrees indoor dry bulb, 75 degrees indoor wet bulb

A. 95 degrees Fahrenheit outside ambient, 80 degrees indoor dry bulb, 68 degrees Fahrenheit wet bulb

Which of the following is accurate about gases? A. A gas must be contained in a closed container or it will escape into the atmosphere B. Gas has a fixed volume that will not change with temperature adjustments C. Gases are not fluid D. Molecules of gases have a lower energy level than solids or liquids

A. A gas must be contained in a closed container or it will escape into the atmosphere

The evaporation process occurs when: A. A liquid is below its boiling point B. A liquid is below its critical pressure C. A liquid is above its critical temperature D. A liquid has reached its critical mass

A. A liquid is below its boiling point

The most relevant standard that applies to air conditioning technicians is:

A. AHRI Standard "A"

A correct statements concerning inertia is: A. All objects that are at rest have the tendency to stay at rest and when in motion tend to stay in motion B. All objects are put into motion by the same amount of force regardless of the quantity of mass C. When dropped from the same height, all objects will hit the ground at the same time regardless of their weight.

A. All objects that are at rest have the tendency to stay at rest and when in motion tend to stay in motion

In contrast to liquids and vapors, solids will: A. Apply only downward pressure when set on a surface B. Apply pressure on the bottom and sides when contained C. React to gravitational force D. Apply pressure in all directions when set on a flat surface

A. Apply only downward pressure when set on a surface

Properties of matter that determine how chemicals react to one another: A. Are known as chemical properties of matter B. Are known as physical properties of matter C. Are tested in pressures above atmosphere D. Are tested in pressures below atmosphere

A. Are known as chemical properties of matter

A thorough knowledge of the properties of matter is necessary to: A. Better understand what happens to various forms of matter and the reasons why changes occur when substances are heated of cooled. B. Design air conditioning equipment and systems for a building structure C. Know where to locate the heating or cooling equipment and system in a building structure

A. Better understand what happens to various forms of matter and the reasons why changes occur when substances are heated or cooled.

Which substance from the choices given has the greatest density? A. Gold B. Aluminum C. Wood D. Copper

A. Gold

How do industry organizations make it easier to compare testing results and rating for HVACR equipment? A. Industry organizations determine a set of standard conditions that make all HVACR testing results comparable B. Industry organizations state that there are too many standards in place to make testing results comparable C. Industry organizations use a set of guidelines that are determined by the individual states

A. Industry organization determine a set of standard conditions that make all HVACR testing results comparable

If something has a high density: A. Its specific volume is likely to be low B. Its specific gravity is likely to be low C. Its specific volume is also likely to be high

A. Its specific volume is likely to be low

The triple point of most substances is: A. Less than atmospheric pressure B. Dependent on barometric pressure above atmospheric and ambient temperatures above 70 degrees Fahrenheit C. Always measured when a substance is in a closed container D. Greater than atmospheric pressure

A. Less than atmospheric pressure

Freezer burn occurs when water slowly exits perishable foods during the freezing process, this process is known as: A. Sublimation B. Deterioration C. Deposition D. Latent change of state

A. Sublimation

The volume of __________is subject to the greatest amount of change when there is a change of pressure and temperature. A. a gas B. a liquid C. a condensate D. a solid

A. a gas

The substance used to compare the specific gravity of gases is:

Air

Matter is defined as:

Anything that has mass and takes up space

When a substance in the liquid state occupies a container it: (pressure)

Applies the greatest amount of pressure to the bottom of the container

The AHRI definition of standard air is: A. 0.75 lb/cubic feet at 75 degrees Fahrenheit B. .075 lb/cubic feet at 70 degrees Fahrenheit C. .075 lb/feet squared at 80 degrees Fahrenheit D. .075 cubic feet/lb and 70 degrees Fahrenheit

B. .075 lb/cubic feet at 70 degrees Fahrenheit

When calculating the specific gravity of gas, the substance used as the comparative constant in the formula is: A. Nitrogen B. Air C. Oxygen D. Natural Gas

B. Air

Which of the following statements are true for matter in a gas state? A. Gas has a definite shape B. Gas will exert equal pressure on all sides when inside a closed container C. Gas has a definite volume D. Gas has the lowest energy level of all states of matter

B. Gas will exert equal pressure on all sides when inside a closed container

The molecules of gases have: A. The same levels of energy as solids and liquids when contained B. Higher energy levels than solids or liquids C. Lower levels of energy than solids or liquids due to molecular instability D. Higher levels of energy than solids or liquids only when exposed to temperature changes

B. Higher energy levels than solids or liquids

When a vapor condenses: A. The amount of energy inside the molecules increase B. The potential energy inside the molecules decrease C. The molecular motion of its atoms increase D. The molecular motion of the atoms ceases

B. The potential energy inside the molecules decrease

In physics, solids and liquids: A. Change when critical pressure is applied to the mass B. Will occupy the same amount of space given the temperature is below 212 degrees Fahrenheit C. Do not change in volume when pressures change, but gas will change D. Change in volume when critical temperature is applied to the mass

C. Do not change in volume when pressures change, but gases will change

When a liquid boils: A. Spontaneous gassification creates new gas molecules B. It is releasing heat while changing from liquid to gas C. It is absorbing heat while changing from liquid to gas D. Its temperature is always 212 degrees Fahrenheit

C. It is absorbing heat while changing from liquid to gas

What is the difference between the weight and mass of an object? A. Mass refers to an object's volume while weight measures the effect of gravity on an object B. Mass and weight both refer to the same physical property C. Mass is not affected by gravity D. Weight is not affected by gravity

C. Mass is not affected by gravity

Specific gravity is defined as: A. The ratio of mass per cubic feet acting upon a given mass B. The time element of inertia in which a specific amount of mass times the distance can be moved C. The ratio of the density of a material as compared to a common material

C. The ratio of the density of a material as compared to a common material

The calculations for density and specific volume for SI are: A. Reciprocal values of ANSI standard conditions B. Inversely proportional when compared with AHRI standard conditions C. The same as AHRI standard conditions using metric values D. Reciprocal values of ACCA standard conditions

C. The same as AHRI standard conditions using metric values

Liquid achieves its boiling point: A. it is below critical pressure B. When the vapor point of the gas bubbles in a liquid becomes lower than the pressure surrounding the liquid C. When the vapor point of the gas bubbles in a liquid becomes equal to the pressure surrounding the liquid D. When the liquid has reached it critical mass

C. When the vapor point of the gas bubbles in a liquid becomes equal to the pressure surrounding the liquid

Changes in the volume of a gas can happen: A. Any time ambient temperature changes and volume of the container doesn't change B. Only if there is change in barometric pressure C. Whenever there is a change in temperature

C. Whenever there is a change in temperature

The nucleus of an atom: A. Produces centrifugal force B. is negatively charged C. is composed of protons and neutrons D. Has a neutral charge

C. is composed of protons and neutrons

What is a practical use for knowing a substance's triple point?

Calibrating thermometers using the triple point temperature

The energy change that takes place when the atoms of materials are rearranged to form new materials from the same atoms is:

Chemical energy

What physical change of state is the opposite of evaporation?

Condensation

What is occurring when gaseous molecules release heat and join together to form a liquid?

Condensing

When a liquid-vapor mix is heated in a closed space, eventually the density of the liquid decreases and the density of the gas increases. When no difference exists between the liquid and the vapor, it has reached its:

Critical point

Which basic principle is one that influences how all HVACR systems work? A. Pressure affects boiling point and evaporation in an unpredictable way, so it must not be considered in HVACR equipment B. A decrease in pressure increases the boiling point of a liquid, the temperature at which a liquid turns to a gas. C. An increase in pressure can lower the boiling point of a liquid and change the temperature at which it turns to a gas D. An increase in pressure can increase the boiling point of a liquid, the temperature at which a liquid turns to a gas

D. An increase in pressure can increase the boiling point of a liquid, the temperature at which a liquid turns to a gas

Specific Volume can be described using which of the following units? A. Pounds per cubic feet B. Ounces per cubic inch C. Pounds per feet squared D. Cubic feet per lb

D. Cubic feet per lb

Specific gravity is used in the HVACR industry: A. For charging air conditioners B. For recovering refrigerant C. For determining system capacity D. For sizing gas lines

D. For sizing gas lines

The reason thermal properties of matter are important is because: A. They determine the relative buoyancy of two liquids at a constant temperature B. They determine if something is wood or metal C. They determine which direction vortexes will form through a restriction D. Heating and air conditioning are about moving heat

D. Heating and air conditioning are about moving heat.

The volume of a solid will: A. Increase as the temperature decreases B. Not change when temperature differences occur C. Decrease when temperature increases D. Increase as the temperature of the solid increases

D. Increase as the temperature of the solid increases

Evaporation occurs: A. Throughout the liquid above the boiling point B. Only above 212 degrees Fahrenheit C. Only above 100 degrees Fahrenheit D. Only on the surface of the liquid

D. Only on the surface of the liquid

Examples of things that do not have mass and are not matter include: A. Hydrogen and methane B. Air and steam C. Helium and argon gas D. Photons and sound

D. Photons and sound

Matter cannot be created or destroyed, but it can and does change form; this statement is known as: A. Dalton's Law of Matter and Energy B. The Second Law of Thermodynamics C. Charles' Law of Kinetic Energy D. The Law of Conservation of Matter

D. The Law of Conservation of Matter

Solids contain _________ amount of energy within materials or substances when they are in their various physical states. A. The highest B. the equivalent C. a variable D. the least

D. the least

The density of a gas that occupies 30 cubic feet and weighs 3 lbs is:

Density= 3 lbs/30 cubic ft= 0.1 lbs/cubic ft

A vapor that changes into a solid while by-passing the liquid state is known as:

Deposition

The state of matter with the highest energy level is:

Gas

Which form of matter has neither a definite shape nor definite volume?

Gas

How does pressure affect the boiling temperature of a liquid?

Increasing the pressure increases the boiling point

A person riding in a car flies forward when the car come to a sudden stop. What concept does this illustrate?

Inertia

The freezing point of a substance:

Is the change of state of a substance from a liquid to solid at a given pressure and temperature when heat is removed

Natural gas will float on air. What does this tell us about its properties?

It has a lower specific gravity than air

If a gas with a specific gravity of 1.3 is released in a room, will it be more likely to be found near the ceiling or near the floor?

It would be found near the floor because its specific gravity is greater than 1

Which units can be used to describe the density of a substance?

Lbs per cubic feet

Which form of matter has a definite volume, but takes the shape of its container?

Liquid

Elements are:

Naturally occurring chemicals

Where is heated air most likely to settle in a room?

Near the ceiling

There are two areas in which the properties of matter can be divided:

Physical and chemical

The state in which a substance exists depends on:

Pressure and temperature

The state of matter with the lowest energy level is:

Solid

As an air-conditioning and refrigeration technician, which of the following states of matter will you use in your job?

Solid, liquid, and gas

When working in the refrigeration and air-conditioning industry, matter is typically encountered in three states:

Solids, liquid, and vapors

The specific volume of a gas that occupies 30 cubic feet and weighs 3 lbs is:

Specific Volume= 30 cubic feet/3 pounds = 10 cubic feet/lb

If a HVACR technician determines the ratio of the density of a material to the density of a common material, what is she calculating?

Specific gravity

What physical change of state is the opposite of deposition?

Sublimation

How do environmental variables complicate the HVACR testing?

Testing conditions, such as air pressure and temperature, can affect testing

When sizing a Btuh load for a refrigeration application, the compressor is rated by:

The amount of refrigerant in cubic feet the compressor can move

It is important to the HVACR technician to understand the changes of state of matter because:

The cooling and heating process requires a change of matter in some form

Weight is defined as:

The force of gravity acting upon an object

Size, form, shape, and state relate to:

The physical state of matter

Define triple point

The pressure and temperature where a substance can exist simultaneously as a solid, a liquid, and a gas in thermal equilibrium

Water will evaporate at a slower rate when:

The relative humidity is high