The compressibility factor $(Z)$ of a gas is greater than unity at $1 \, atm$ and $273 \, K$. Therefore:

Under which one of the following conditions do real gases approach the ideal gas behaviour?

The compressibility factor $(Z)$ of a gas is less than unity at $STP$. Therefore:

What is compressibility factor $(Z)$? Explain $(i)$ deviation factor $(Z = 1)$,$(ii)$ $Z > 1$,$(iii)$ $Z < 1$,$(iv)$ deviation graph,and $(v)$ the relation between molar volume and $Z$.

Van der Waals equation for a gas is stated as,
$p = \frac{nRT}{V - nb} - a\left( \frac{n}{V} \right)^2$
This equation reduces to the perfect gas equation,$p = \frac{nRT}{V}$,when:

Identify the conditions at which the van der Waals equation of state changes to the ideal gas equation.