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

Answer: Option A

Given:

Dry bulb temperature = 60°C

Dew point temperature = 40°C

Total pressure = 101.3 kPa

Vapour pressure of water at 40°C = 7.30 kPa

Vapour pressure of water at 60°C = 19.91 kPa

Humidity (H) is calculated using:

H = 0.622 × (P_v / (P - P_v))

Where:

P_v = partial pressure of water vapour = vapour pressure at dew point = 7.30 kPa

P = total pressure = 101.3 kPa

Now substituting the values:

H = 0.622 × (7.30 / (101.3 - 7.30))

H = 0.622 × (7.30 / 94.0)

H ≈ 0.622 × 0.07766

H ≈ 0.0482 kg water/kg dry air

Therefore, the correct answer is Option A: 0.048