Question

Why can we smell hot food from a distance?

Answer 1

All substances in the universe are made up of a material called matter. It is something which has both space and mass. It contains small particles in it which are always moving. They have a force of attraction between them.

Complete step by step answer:
An example for showing that matter has space is the coffee or tea. When we are preparing tea or coffee, particles of one type of matter move into the spaces between the particles of other types. All types of matter have atoms in it, i.e. matter is made up of atoms. The movement of the particles in all the states of matter is very rapid at room temperature. These particles collide with each other. Thus the kinetic energy of the particles are constant and thereby total energy is conserved. The movement of particles in solids, liquids and gases are different. In solids, the particles are packed tightly in an ordered way. The force of attraction between the particles in solids is very strong while it is very weak in liquids and gases.
We know that diffusion occurs when there is a movement of particles. The movement of particles from higher concentration to lower concentration occurs till a uniform distribution is attained. When we increase temperature, the particles move with more speed and gain kinetic energy. Hot food has a very high temperature. Thus it spreads to a very large distance.
So we can say that we smell hot food from a distance because of diffusion.

Note: When the temperature is increased, the rate of collision of particles will be more. Thus it vibrates faster and more strongly. The state of a substance can be changed by changing its environment. When temperature is increased, we can change a solid to liquid or gas.