Chapter 1

NCERT
Class 9
Science
Solutions
3. 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.

Question:

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.

Answer:

(a) The particles of gas are separated from each other and they have large space between them, due to this they have ability to flow. Thus gas fills completely in the vessel.

(b) The gas particles move randomly hire and there. So they exert pressure on the wall of container.

(c) The particles of wood are bound with strong molecular force. So it is named as solid wooden. Table is a converted form of wood so it is a solid.

(d) We can move our hand in air because there is enough space between particles of air by which they can be easily resist. So, less force works in the air. There is very small space between particles of wood so. We cannot move our hand between them by applying a large force. If you force, you will end up hurting your hand, hurting your hand we force we will hurt air hand. Therefore it is solid that for moving hand in wood we should be proficient in Karate.

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