What is an ideal gas ? Why do the real gases show deviations from ideal behaviour?

cbse
kinetictheoryofgases

#1

A gas which obeys the ideal gas equation PV = nRT at all temperatures and P is called ideal gas equation.
The two assumptions are :
(1) The size of the gas molecules is negligibly small.
(2) There is no force of attraction amongst the molecules
of the gas.