Gas is a physical state of matter. In this physical state, the particles can move randomly. This is because of high kinetic energy of molecules. We can notice this in our everyday life. i) When we spray perfume in a room, we can smell it even from far enough. This is because, the gaseous particles of perfume can diffuse easily from one place to another. ii) When we prepare food in kitchen, we can smell the scent of yummy food in next room also that is because of the continuous movement of gas particles of aroma of food.