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?

For a real gas at $25^{\circ} C$ temperature and high pressure $(99 \ bar)$,the value of the compressibility factor is $2$. The value of the Van der Waals constant '$b$' is $\times 10^{-2} \ L \ mol^{-1}$. (Nearest integer) (Given $R = 0.083 \ L \ bar \ K^{-1} \ mol^{-1}$)

The given graph represents the variation of $Z$ (compressibility factor = $\frac{PV}{nRT}$) versus $P$,for three real gases $A, B$ and $C$. Identify the only incorrect statement.

At low pressure,the van der Waals equation becomes:

Which of the following gas samples shows real gas behavior?

Define the compressibility factor $(Z)$ in terms of the molar volume of a gas.