Unit 35 Quiz and Test Review

A

Relative humidity is measured using which of the following instruments A. Psychrometer B. Thermotyporiter C. Volt-ohm milliammeter D. Dry-bulb thermometer

False

Specific heat is the total heat content of air and has both sensible and latent heat components True or False

B

What is the dew point temperature of a 75 degrees F air sample with a relative humidity of 60%? A. 58 degrees F B. 60 degrees F C. 62 degrees F D. 64 degrees F

False

When using sling psychrometer ONLY tap water should be used True or False

B

Which of the following is a correct formula for total heat? A. QT = Qs - QL B. QT = Qs + QL C. QT = Qs x QL D. QT = Qs / QL

B

Which of the following statements is true regarding the heating of an air sample? A. The dry-bulb temperature will rise and the wet-bulb temperature will drop B. The relative humidity will drop and the absolute humidity will remain the same C. The dry-bulb temperature will drop and the wet-bulb temperature will rise D. The relative humidity will rise and the absolute humidity will remain the same

B

Enthalpy is expressed in which of the following units? A. ft cubed/lb B. Btu/lb C. lb/ft cubed D. lb/Btu

C

Of the following sets of air properties, which two can be identified by following the same line? A. Wet-bulb temperature and dry-bulb temperature B. Relative humidity and absolute humidity C. Enthalpy and wet-bulb temperature D. Absolute humidity and dry-bulb temperature

D

On the psychrometric chart, the scale along the bottom of the chart represents A. wet-bulb temperature B. dew point temperature C. enthalpy D. dry-bulb temperature

D

The body gives off heat in all of the following ways except A. conduction B. convection C. radiation D. condensation

D

A measurement of the heat content of air, expressed in BTU per pound of air, is called _______________ A. specific heat B. dry-bulb C. density D. enthalpy

B

A wet-bulb thermometer has a wick over the end of it. The wick should be soaked with ________________ for an accurate reading A. tap water B. distilled water C. hydrogen peroxide D. alcohol

D

A(n) ____________________ heat transfer is one that represents a change in the state of a substance with not change in temperature A. sensible B. conductive C. radiant D. latent

B

According to the summer comfort chart, Figure 35.6 (A), people will generally be comfortable when exposed to which of the following sets of conditions? A. 70 degrees F @ 50% relative humidity B. 75 degrees F @ 50% relative humidity C. 80 degrees F @ 50% relative humidity D. 85 degrees F @ 50% relative humidity

A

According to the winter comfort chart, Figure 35.6 (B), people will generally be comfortable when exposed to which of the following sets of conditions? A. 70 degrees F @ 50% relative humidity B. 75 degrees F @ 50% relative humidity C. 80 degrees F @ 50% relative humidity D. 85 degrees F @ 50% relative humidity

C

Air is made up of several different gases with a composition of ___________________ A. oxygen 78%, other gases 21%, nitrogen 1% B. oxygen 78%, nitrogen 21%, other gases 1% C. nitrogen 78%, oxygen 21%, other gases 1% D. nitrogen 78%, other gases 21%, oxygen 1%

D

Air is primarily made up of A. 78% oxygen, 21% nitrogen B. 25% nitrogen, 75% oxygen C. 50% oxygen, 50% nitrogen D. 78% nitrogen, 21% oxygen

D

Air that contains all of the moisture that it can hold is referred to as being A. subcooled B. superheated C. sublimated D. saturated

A

At standard atmospheric pressure, air has a density of A. 0.075 lb/ft cubed B. 0.75 lb/ft cubed C. 1.33 lb/ft cubed D. 13.33 lb/ft cubed

A

Comfort is a balance of what components? A. Temperature, Humidity, Air Movement, Air Cleanliness B. Temperature, Humidity, Fresh Air C. Dry-bulb, Wet-bulb, Dew Point D. Cool air, Warm air, Clean air, Humid air

A

Condensate dripping from an air-conditioning system is an indication that the evaporator coil temperature is A. cooler than the air's dew point temperature B. warmer than the air's dew point temperature C. cooler that the air's dry-bulb temperature D. warmer than the air's dry-bulb temperature

B

If an air sample holds 60 grains of moisture (per pound) and has the ability to hold a maximum of 90 grains of moisture (per pound), what is the relative humidity of the air sample? A. 33% B. 67% C. 100% D. 150%

A

If only the absolute humidity of an air sample is known, which of the following values can be determined from the psychrometric chart? A. Wet-bulb temperature B. Dew point temperature C. Enthalpy D. Dry-bulb temperature

B

If the density of a gas is 0.5 lb/ft cubed, what is its specific volume? A. 1 ft cubed/lb B. 2 ft cubed/lb C. 4 ft cubed/lb D. 8 ft cubed/lb

A

If the dry-bulb temperature is 75 degrees F and the wet-bulb temperature is 60 degrees F, the wet-bulb depression is A. 15 degrees F B. 30 degrees F C. 60 degrees F D. 75 degrees F

D

Multiplying the density of a gas and its specific volume together will always produce a result equal to A. 4 B. 3 C. 2 D. 1

A

The _____________________ is the temperature at which moisture begins to condense out of the air A. dew point temperature B. wet-bulb temperature C. wet-bulb depression D. dry-bulb temperature

A

The actual amount of water vapor contained in an air sample is referred to as ______________ and is usually expressed in grains of moisture per pound of air A. absolute humidity B. wet bulb C. relative humidity D. latent heat

B

If the human body is exposed to very warm temperatures, which of the following is true? A. Perspiration will form to warm the body B. Perspiration will form to cool the body C. Respiration will form to warm the body D. Respiration will form to cool the body

D

If the wet-bulb depression is 0 degrees F, what is the relative humidity of the air sample? A. 25% B. 50% C. 75% D. 100%

D

In a cooling-only process, all of the following are true except A. the dry-bulb temperature drops B. the wet bulb temperature drops C. the specific volume of the air drops D. the absolute humidity drops

C

In order for an evaporator to remove moisture from the airstream passing through it, the evaporator coil must be at a temperature that is lower than the air's A. wet-bulb temperature B. dry-bulb temperature C. dew point temperature D. critical temperature

C

In the winter, lower room temperatures can be offset by A. lowering the absolute humidity B. avoiding strenuous activities C. increasing the relative humidity D. opening the structure's doors and windows

A

The difference between the dry-bulb reading and the wet-bulb reading is called ___________________ A. wet-bulb depression B. absolute humidity C. dry-bulb depression D. relative humidity

True

The gases that make up the earth's air are highly superheated, several hundred degrees above absolute zero (0 degrees Rankine) True or False

C

The nitrogen and oxygen in our air are classified as A. inert gases B. subcooled gases C. superheated gases D. saturated gases

B

The study of air and its properties is called _________________ A. ventilation B. psychrometrics C. indoor air quality (IAQ) D. generalized comfort

B

The term enthalpy applies to A. a combination of hidden heat and latent heat B. a combination of latent heat and sensible C. the latent heat portion of an air-conditioning process D. the sensible heat portion of an air-conditioning process

B

The term used to describe the random air that leaks into a structure is A. ventilation B. infiltration C. exhaust D. exfiltration

C

Which of the following is true regarding wet-bulb and dry-bulb temperatures? A. The wet-bulb temperature reading is never lower than the dry-bulb temperature B. The wet-bulb temperature reading is always lower than the dry-bulb temperature C. The wet-bulb temperature reading can be equal to the dry-bulb temperature D. The wet-bulb temperature reading is always equal to the dry-bulb temperature