Amount of water vapour (gaseous) in a given volume of air (cubic metre) is known as: (1) Mixing ratio (2) Relative humidity (3) Absolute humidity (4) Specific humidity
(3) Absolute humidity Explanation: The relative humidity of air at a given temperature is the ratio of mass of water vapour actually present in a certain volume of air to the mass of water vapour required to saturate the same volume of air at the same temperature, multiplied by 100.