Question

How can gas pressure be defined at molecular level?

Answer 1

Pressure can be defined as a force which the substance exerts on another substance per unit area and pressure of the gas is the force exerted by the gas on the boundaries of the container. Gas molecules have very less force of attraction so they move freely in nature.

Complete answer:
Gas molecules move randomly along the given volume and during this
movement they collide with the surface and with each other. These molecules constitute the gas pressure in combined form, greater the number of collisions then higher the pressure. Formula for calculating gas pressure can be defined as follows:
$P=\dfrac{F}{A}$
Where F is the force exerted due to collisions, P is the pressure and A is the area.
Rather than this ideal gas pressure is also given by the following manner
$P=\dfrac{nRT}{V}$
Where n = number of moles, R = Gas constant, T = temperature and V = volume
From this equation we can conclude that the pressure of the gas is thus proportional to the number of particles colliding or we can say that frequency of collisions in unit time per unit area on the wall of the container.
The SI unit of gas pressure is expressed in the form of Pascal represented by the symbol Pa.

Note:
Molecular level expresses the compound which is in association with two or more atoms. The main example of molecules is water molecule which is a combination of two hydrogen atoms and one oxygen atom.