Answer
The random motion of molecules occurs when they are placed in any container any open space, they have freedom to move to and fro as well as from one point to another. The random movement of molecules do not needs any energy inputs and it occurs on its own.
Diffusion:
If we talk about diffusion, it is a process in which molecules move from an area of higher concentration towards an area of lower concentration. For example: When we spray a fragrance in one corner of the room, after some time it will spread in whole room because molecules will move from a corner of high molecular concentration to the place where they are less in number. This process occurs freely and without any external input of energy.
Osmosis:
If we talk about osmosis it is also a diffusion of molecule but across a selectively permeable membrane like plasma membrane of living cells. Just like simple diffusion it also donot needs any external energy inpuy.
What is common in all?
That all three types of molecular movements do not need any energy inputs from system and it occurs on their own, therefore all are related.
Hope it help!
