What are the values of $V_C$,$P_C$,and $T_C$ in terms of van der Waals constants $a$ and $b$?

Which among the following statements is/are incorrect regarding real gases?
$(i)$ Their compressibility factor is never equal to unity $(Z \neq 1)$.
$(ii)$ The deviations from ideal behavior are less at low pressures and high temperatures.
$(iii)$ Intermolecular forces among gas molecules are equal to zero.
$(iv)$ They obey Van der Waals equation,$PV = nRT$.

If the inversion temperature of a gas is $-80\,^{\circ}C$,then it will produce cooling under the Joule-Thomson effect at ............... $K$.

$A$ real gas obeying Van der Waals equation will resemble an ideal gas if the:

For real gases,the relation between $P$,$V$ and $T$ is given by the van der Waals equation,$(P + \frac{an^2}{V^2})(V - nb) = nRT$. For the following gases $CH_4, CO_2, O_2, H_2$,which gas will have $(i)$ highest value of $'a'$ $(ii)$ lowest value of $'b'$?

Pressure exerted by $1 \, mole$ of methane in a $0.25 \, L$ container at $300 \, K$ using van der Waals equation is ............... $atm$ (given $a = 2.253 \, atm \, L^2 \, mol^{-2}, b = 0.0428 \, L \, mol^{-1}$):