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 the air, but to do the same through a solid block of wood, we need a karate expert.

Liquids generally have a lower density than solids. But you must have observed that ice floats on water. Find out why.

What is the physical state of water at?

(a) 250°C

(b) 100°C

For any substance, why does the temperature remain constant during the change of state?