Q.Name the term used for mixing of different gases by random molecular motion and ferquent collision.

A gas sample is fully characterised by four interrelated measurable quantities. Mass (m), SI unit kilogram, relates to moles via n = m/M. Volume (V), the space a gas occupies, is commonly measured in litres or cubic metres (SI); since a gas takes the volume of its container, gas volume really means container volume. Pressure (P), force per unit area (P = F/A), has the SI unit pascal (Pa = N/m^2); common non-SI units include bar (1 bar = 1.00x10^5 Pa) and atmosphere (1 atm = 760 mm Hg = 760 torr = 101.325 kPa); gas pressure is measured with a manometer, atmospheric pressure with a barometer. Temperature (T), on the Celsius or, more usefully for gas laws, the absolute Kelvin scale (T(K) = t(deg C) + 273.15), determines the direction heat flows between objects in contact. Related derived properties include density (d = m/V, or vapour density = molar mass/2 relative to hydrogen) and the rate of diffusion (volume diffused per unit time). All of the gas laws are, at heart, statements about how these measurable properties are related to one another.