(i) The increasing order of ‘b’ is as follows:
He < H2< O2< CO2. As the Vander Waals constant ‘b’ is approximately equal to the total volume of the molecules of a gas.
(ii)The decreasing order will be:
CH4> O2> H2 as the surface area of CH4 is highest so, it has highest Vander Waal’s force of attraction so, has the highest value of ‘a’, followed by O2 and H2.