Under which conditions do real gases deviate most from ideal gas behavior?

The Van der Waals equation reduces itself to the ideal gas equation at

The temperature at which the second virial coefficient of a real gas is zero is called:

Which of the following formulae is used to determine the compressibility factor $(Z)$ for the measurement of deviation from ideal behavior?

The $P$ vs $V$ graph is plotted for $1$ $mole$ of a hypothetical gas. Based on the given isotherms at $200 \ K$ and $300 \ K$,determine the range of $\frac{a}{b}$ for this gas in $atm-L \ mole^{-1}$. [Given: $R = 0.08 \ atm-L \ mole^{-1} \ K^{-1}$]

When helium gas is allowed to expand into vacuum, a heating effect is observed. The reason for this is (assume $He$ as a non-ideal gas):