Gases deviate from the ideal gas behaviour because their molecules

The compressibility factor $(z)$ is lower for $NH_3$ and $CO_2$ gases than that of $N_2$ gas, because

Which of the following formulas is used to calculate the compressibility factor?

For a non-ideal gas,identify the term in the van der Waals equation that represents the intermolecular forces.

What is the Boyle temperature?

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: $R = 0.08 \ atm-L \ mole^{-1} \ K^{-1}$]