hello sir,

i want to know that on absolute zero both pressure and volume are zero why ?

Is boyle's law if only followed by the gas for compression or it will valid for expansion also ?

correct defination of pressure.

charle's laws is only followed in low pressure and high temp why?

Umm, after all molecular activity stops, how're you going to have pressure or volume?

Boyles law is valid for both in ideal cases. Dont think Charles law implied what you're saying. Heh, think of it this way, a P vs. V graph is always a rectangular hyperbola, and a V vs T (in K) is always a straight line.

Pressure definition wise is Force upon unit area, there is no more. As for causes, its due to collisions of molecules of the fluid on the surface of the container.

Niraj sir please answer my question....
molecular activity stops completely. Does that mean velocity of molecules is zero?
If yes, wudn't that be a violation of uncertainty principle?

how this could be possible that at absolute zero volume becomes zero
as far as uncertainity principle is concerened it tells that t is not possible to know both velocity as wellas position of the electron at any instant of time . at absolute zero you only know that electron is at rest not the position

if all molecular activity stops how it will affect volume

Okay, easier way to explain it..

PV = nRT
=> PV = 0 (since T = 0)

Also valid for the real gas relations.