$A$ real gas would be most likely to obey the ideal gas laws at

For the following gases,the values of $'a'$ (van der Waals constant) are given in parentheses: $CH_4 (2.25)$,$N_2 (1.35)$,$O_2 (1.36)$,and $CO (1.46)$. Which gas will be the most difficult to liquefy?

The compressibility factor $(Z)$ of one mole of a van der Waals' gas of negligible '$a$' value is

At high pressure,the van der Waals equation for a real gas reduces to:

Which statement is correct regarding a real gas?

$A$ gas deviates most from ideal behavior when it is subjected to