Absolute or specific humidity is

Absolute or specific humidity is

a) the actual mass of moisture present in a specific amount of air
b) the maximum mass of moisture that a specific amount of air can hold
c) the ratio of the mass of moisture contained in a specific amount of air to the maximum amount of moisture this specific amount of air can contain
d) the mass of moisture present in a specific amount of air at that absolute temperature
e) a specific amount of air saturated with moisture





Answer: A

The term "relative humidity" applies to

The term "relative humidity" applies to

a) the percentage of moisture in the air as compared to the amount of moisture the air can hold at a specific temperature
b) the weight of the moisture in the air
c) the dryness fraction of the air
d) the amount of moisture in the air
e) the amount of humidity in the air







Answer: A

Air conditioning involves

Air conditioning involves

a) only the cooling of the air in a conditioned space
b) the control of the air temperature, the control of humidity, air circulation, and the removal of contaminants
c) only the control of air temperature
d) only the control of humidity and temperature
e) only air purification






Answer: B

Relative humidity is

Relative humidity is

a) the ratio of water vapour in the air compared to the total amount water vapour the air could contain at a given temperature
b) equal to the dry bulb temperature divided by the wet bulb temperature
c) equal to the wet bulb temperature divided by the dry bulb temperature
d) the ratio of the mass of water vapour divided by the mass of dry air
e) the ratio of the mass of water vapour divided by the mass of wet air







Answer: A

Dalton's Law of partial pressure states that

Dalton's Law of partial pressure states that

a) for every pressure there is an equal and opposite pressure
b) in a mixture of two or more gases each will exert a partial pressure which is equal to the pressure that it would exert if it filled that space alone
c) the pressure exerted by two or more gases on the walls of the containing vessel is equal to a constant
d) the sum of the mass of air and water vapour in a vessel is equal to the total pressure
e) water vapour must be included when calculating air pressures






Answer: B

Which of the following instruments use a battery operated fan to draw air over thermometer bulbs?

Which of the following instruments use a battery operated fan to draw air over thermometer bulbs?

a. Hydrometer
b. Aspirating psychrometer
c. Sling psychrometer
d. Dry psychrometer
e. Humidistat






Answer: B

The dry-bulb temperature scale is read on a psychrometric chart along the:

The dry-bulb temperature scale is read on a psychrometric chart along the:

a. Left vertical axis
b. Right vertical axis
c. Saturation line and sloping downward to the right
d. Top horizontal axis
e. Horizontal axis on the bottom of the chart







Answer: E

The specific humidity scale on a psychrometric chart is along the:

The specific humidity scale on a psychrometric chart is along the:

a. Bottom horizontal axis
b. Right side vertical axis
c. Top horizontal axis at the top of the chart
d. Left saturation line
e. Left-side vertical axis and left side






Answer: B

The heat content of air is called the _____ of the air.

The heat content of air is called the _____ of the air.

a. Temperature
b. Humidity
c. Enthalpy
d. Psychrometry
e. Entropy







Answer: C

Which of the following instruments use a battery operated fan to draw air over thermometer bulbs?

Which of the following instruments use a battery operated fan to draw air over thermometer bulbs?

a. Hydrometer
b. Aspirating psychrometer
c. Sling psychrometer
d. Dry psychrometer
e. Humidistat








Answer: B

Dew point can be best defined as the:

Dew point can be best defined as the:

a. Absolute temperature at which air, upon heating, will evaporate moisture
b. Percentage of moisture that air can hold at a given temperature and pressure
c. Temperature that air will begin to evaporate moisture
d. Temperature at which air, upon cooling, becomes saturated, causing moisture to condense should the temperature drop further
e. Atmospheric pressure at which air will condense moisture








Answer: D

In the S.I. (metric) system the enthalpy of air is measured in:

In the S.I. (metric) system the enthalpy of air is measured in:

a. degrees Celsius
b. percent
c. BTU/kg of dry air
d. kJ/kg of dry air
e. kW/kg of dry air








Answer: D

Dry-bulb temperature is:

Dry-bulb temperature is:

a. The absolute temperature corresponding to the atmospheric pressure
b. The same as the wet-bulb temperature if the relative humidity is less than 100%
c. Not required to find the relative humidity
d. The temperature of the air measured with an ordinary thermometer
e. The dew point temperature







Answer: D

On a psychrometric chart, the dewpoint temperature may be read along the:

On a psychrometric chart, the dewpoint temperature may be read along the:

a. Top horizontal axis
b. Same scale as the moisture content
c. Horizontal axis on the bottom of the chart
d. Right hand vertical axis
e. Left vertical axis







Answer: D

Standard air is the:

Standard air is the:

a. Mass of 1 cubic meter of dry air at 20°C and atmospheric pressure
b. Mass of a cubic meter of air at atmospheric conditions
c. Volume of air at ambient temperature and atmospheric pressure
d. Volume of 1 kg of dry air at 21°C and atmospheric pressure at sea level or 101.325 kPa
e. Volume of 1 kg of air at 15°C and 100 kPa









Answer: D

Enthalpy of air depends on the:

Enthalpy of air depends on the:

a. Pressure, temperature and relative humidity of the air
b. Relative humidity of the air only
c. Pressure and temperature of the air only
d. Air velocity
e. Temperature of the air only







Answer: A

A device for measuring relative humidity is called:

A device for measuring relative humidity is called:

a. A dew point analyzer
b. An R. H. gauge
c. An aspirating gauge
d. A psychrometer
e. A chronometer







Answer: D

Wet-bulb temperature is:

Wet-bulb temperature is:

a. The temperature indicated by a thermometer whose bulb covered by a water-wetted wick and exposed to a rapidly moving stream of air
b. The same as the dry-bulb temperature if the relative humidity is less than 100%
c. The dew point temperature
d. Always less than the dry-bulb temperature
e. Not required to find the relative humidity

Answer: A

Air that is fully saturated has a relative humidity of:

Air that is fully saturated has a relative humidity of:

a. 90%
b. 96.8%
c. 100%
d. 101%
e. 10%







Answer: C

The specific volume on a psychrometric chart:

The specific volume on a psychrometric chart:

a. Is plotted on vertical lines and read on the horizontal scale at the bottom of the chart
b. Is plotted on horizontal lines and read on the vertical scale on the left side of the chart
c. Is plotted on horizontal lines and read on the vertical scale on the right side of the chart
d. Has its lines originate on the volume scale along the saturation line which slope steeply down to the right of the chart
e. Is plotted on vertical lines and read on the horizontal scale at the top of the chart

Answer: D