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
Answers
(a)Gases have a negligible intermolecular force of attraction between the particles of gas. As a result, the random motion of particles in all directions is experiencing in the vessel. Hence, the gas fills the vessel in which it is kept.
(b)They have high kinetic energy and negligible force of attraction to move constantly moving with high speed in all directions. Due to this intense random motion of particles, the particles hit each other and hit the container walls with force. These collisions of the gas particles with the container walls exert pressure on the walls of the container.
(c)A wooden table should be called a solid because
i)It has a definite shape and volume.
ii)It is very rigid and cannot be compressed, i.e., it has a solid characteristic.
iii)There is a strong force of attraction between molecules of wood, and intermolecular space is the least.
iv)The table does not flow when placed.
As the wooden table acquires all the characteristics of a solid (that is, fixed shape, volume, rigidity, strong force of attraction, least intermolecular space), the wooden table should be called solid.
(d)i)Molecules in gases are loosely packed as compared to solid molecules, which are densely packed. So we can easily break the force of attraction when we move our hand through the air, but it is difficult to break through a solid due to the greater forces of attraction between molecules.
ii)The particles of the air have large intermolecular spaces and the least force of attraction between them. On the other hand, the solid particles have a minimum amount of intermolecular space and maximum force of attraction between them. Thus, a greater amount of force is required to move the particles of solid apart. Thus, a much greater force is required to move hand through a solid block of wood.
So we need a karate expert to break the solid block of wood.