Answer:
Diffusion
Explanation:
The process by which substances move from areas of higher concentration to areas of lower concentration is called diffusion.
For example:
Substance moves across a cell membrane without using the cell's energy tends to move away from the area where it is more concentrated.
It is known as passive transport.
It is the process in which substance without using the cellular energy tend to move down the concentration gradient.
It is also known as simple diffusion.
When perfume bottle is open particles spread in air due to difference in concentration from bottle to out side environment.
While,
In case of active transport substance move against the concentration gradient i.e to wards the area of higher concentration.
This process require energy.
