Q103
General SciencePhysics
On average, air contains ______ % of water vapour.
- a.1
- b.3
- c.5
- d.7
Answer: (A) 1
Water vapour is a variable gas of the atmosphere: it ranges from almost nil in cold dry air to about 4 per cent in warm humid tropics, and the average near the surface is taken as about 1 per cent. Fixed composition of dry air for comparison: nitrogen 78 per cent, oxygen 21 per cent, argon 0.93 per cent, carbon dioxide about 0.04 per cent. Water vapour is also an important greenhouse gas.