The mass of water vapour in a given volume of air is 0.05g at 20°C, while the mass of water vapour required to saturate it at the same temperature is 0.15g. Calculate the relative humidity of the air.

A.

3.33%

B.

5.55%

C.

33.33%

D.

55.55%

Correct answer is C

RH = mass of water vapour in volume of air
mass of water vapour for saturation

 

RH = m
M
= 0.05
0.15
× 100 = 5
0.15
= 500
15
= 33.33%