Question

why helium shows only positive deviation from ideal gas behaviour ?

Answer 1

according to ideal gas equation PV=nRT
an ideal gas obeys this equation through all P & T ranges
however real gases donot always obey this gas law
hence a factor called as compressibility factor Z is introduced
when PV=nRT then Z is assumed to be 1
in case of a real gas Z maybe greater or smaller than 1
if Z>1 then gas is more compressible and shows a negative deviation from ideal gas behaviour
if Z<1 then gas is less compressible and shows positive deviation from ideal gas behaviour
helium is more compressible and hence shows a +ve deviation........hope my answer hepled if it really did then plsss do mark this one as the brainlist answer