Class 9 Science - Chapter Matter in Our Surroundings NCERT Solutions | Give reasons (a) A gas fills complete
Give reasons
(a) A gas fills completely the vessel in which it is kept.
(b) A gas exerts pressure on the walls of the container.
(c) A wooden table should be called a solid.
(d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.
(a) Since the attraction force between particles of a gas in negligible i.e., that is extremely less hence particles freely move in all possible directions as a result gas fills completely the vessel in which it is kept.
(b) Freely moving particles of gas hit the walls of its container continuously and randomly therefore such random and erratic motion of gas particles exerts pressure on the walls of the container.
(c) A wooden table should be a solid because the particles of wooden table are quite rigid, have a fixed location and also possess a definite shape and volume. Due to all these properties we should call a wooden table a solid substance.
(d) Air is a mixture of gases and since particles of gal are far apart so the name is true for air therefore we can easily move our hand in air. But a solid block of wood is hard and rigid that resists any change in location of its particles hence we need a karate expert in case of a solid block of wood.
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