At relatively high pressure,the van der Waals equation becomes?

What is the difference in the pressure-volume $(P-V)$ graph (at constant $T$) for a real gas and an ideal gas?

When does a gas deviate the most from its ideal behaviour?

In $Vander$ $Waal$'s equation of state for gases,the constant '$b$' is a measure of

The values of van der Waals' constant '$a$' for gases $O_2, N_2, NH_3$,and $CH_4$ are $1.360, 1.390, 4.170$,and $2.253 \ L^2 \ atm \ mol^{-2}$ respectively. The gas which can be most easily liquefied is

Positive deviation from ideal behaviour is due to the fact that