can somebody explain Why the liquids that are denser, place lower than those who have a lower density from a macroscopic and microscopic point of view??
1) Liquids don't resist to shear stresses, or the resistance is very low.
2) Liquid molecules vibrate.
These 2 reasons explain why it is possible to have a layer of sand, and over there a layer of iron powder, and the denser iron powder layer stays there, doesn't swap position with sand. They resist to shear stresses and don't move.
Suppose there are two liquids A and B placed together. The answer to your completely depends upon the buoyant force exerted by on liquid on the other.
The equation of this buoyant force is:
F = ρVg
Where F is the buoyant force (say applied on A by B), ρ is the density of the liquid (say B), V is the volume (say volume of A).
As you can see from this equation, buoyant force acting on any object is directly proportional to the density of the liquid that it is placed in. This means that if the liquid is denser, then it will apply a relatively large magnitude of buoyant force on that object, hence pushing it against the direction of gravity, which gives us the thought that the object is floating.
This is the reason why denser things are found near the bottom and relatively less dense things are found towards the top (float).