The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called

Consider the following statements and choose the correct answer:
1. A direct proportionality exists between vapour pressure and the concentration of water vapour in the atmosphere
2. Relative humidity is an expression of the ratio of the actual vapour pressure of the atmosphere when saturated at the same temperature
3. A rise or fall in temperature with no change in vapour pressure will cause a drop or rise, respectively, in relative humidity
4. A rise or fall in vapour pressure with no change in temperature will be accompanied by a rise or fall, respectively, in relative humidity

A

1, 2, 3 and 4 are true

B

Only 3 and 4 are true

C

Only 2 and 4 are true

D

Only 1, 2 and 3 are true

The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure, is called

A

Humidity ratio

B

Relative humidity

C

Absolute humidity

D

Degree of saturation

What is the ratio of actual mass of water vapor in a given volume of moist air to the mass of water vapor in the same volume of saturated air at the same pressure and temperature?

A

Specific Humidity

B

Relative humidity

C

Degree of saturation

D

Saturated air

A vessel of volume 1000 m³ contains air which is saturated with water vapour. The total pressure and temperature are 100 kPa and 20°C respectively. Assuming that the vapour pressure of water at 20°C is 2.34 kPa, the amount of water vapour (in kg) in the vessel is approximately

A

17

B

20

C

25

D

34

What is the ratio of actual mass of water vapor in a unit mass of dry air to the mass of water vapor in the same mass of dry air when it is saturated at the same temperature?

A

Moist air

B

Dry air

C

Degree of saturation

D

Saturated air

An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is

A

0.048

B

0.079

C

0.122

D

0.152

Saturated solution of benzene in water is in equilibrium with a mixture of air and vapours of benzene and water at room temperature and pressure. Mole fraction of benzene in liquid is x_B and the vapour pressures of benzene and water at these conditions are P_v^B and P_v^w respectively. The partial pressure of benzene in air-vapour mixture is

A

PvB

B

XB.PvB

C

(Patm - Pvw)xB

D

XB.Patm

Relative humidity is given by (where p_v = Partial pressure of water vapour, p_b = Barometric pressure, p_s = Pressure of saturated air, p_d = Pressure at dry bulb temperature, p_w = Saturation pressure corresponding to wet bulb temperature and $$\mu $$ = Degree of saturation)

A

$$\frac{{0.622{{\text{p}}_{\text{v}}}}}{{{{\text{p}}_{\text{b}}} - {{\text{p}}_{\text{V}}}}}$$

B

$$\frac{\mu }{{1 - \left( {1 - \mu } \right)\frac{{{{\text{p}}_{\text{s}}}}}{{{{\text{p}}_{\text{b}}}}}}}$$

C

$$\frac{{{{\text{p}}_{\text{v}}}\left( {{{\text{p}}_{\text{b}}} - {{\text{p}}_{\text{d}}}} \right)}}{{{{\text{p}}_{\text{d}}}\left( {{{\text{p}}_{\text{b}}} - {{\text{p}}_{\text{v}}}} \right)}}$$

D

None of these

Suppose saturated polar air has an air temperature and dew point of -10o C, and unsaturated desert air has an air temperature of 35o C and a dew point of 10o C. The desert air contains water vapour and has a __ relative humidity than the polar air.

A

More, lower

B

More, higher

C

Less, lower

D

Less, higher

For an air(A)-water vapour(B) mixture, the partial pressure of the air is 5 pa and the total pressure of the system is 15 pa. The absolute humidity in mass of air/mass of water vapour is

A

0.805

B

0.311

C

0.705

D

0.411