Question Text
Question 1 :
The layer of air around the earth is known as ___________.
Question 6 :
The animals living in water use the dissolved ____ in water for respiration.
Question 10 :
Until the eighteenth century, people thought that air was just ___ substance.
Question 11 :
When air comes in contact with a cool surface, it ______.
Question 14 :
Why do mountaineers carry oxygen cylinders with them, while climbing high mountains?
Question 15 :
Air helps in the movements of sailing yachts, gliders, parachutes and aeroplanes.
Question 16 :
Presence of water vapour in the atmosphere is important for the ______ .
Question 20 :
Air helps in the dispersal of seeds and pollen of flowers of several plants.
Question 22 :
The component of air used by green plants to make their food, is ___________.
Question 23 :
The presence of dust particles in air varies from time to time, and from place to place.
Question 25 :
Birds, bats and insects can fly in the absence of air .