The van der Waals' equation for a real gas is given by the formula $\left(p+\frac{n^{2}a}{V^2}\right)\left(V-nb\right)=nRT, \mathrm{w}\mathrm{h}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{ }p, V, T \mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }n$ are the pressure, volume, temperature and the number of moles of the gas. Which one is the correct interpretation for the parameter $a?$

For a van der Waals' gas, the term $\left(\frac{\mathrm{ab}}{{\mathrm{V}}^2}\right)$ represents some

The unit of the van der Waals gas equation parameter $\text{'}\mathrm{a}\text{'}$ in $\left(\mathrm{P}+\frac{{\mathrm{an}}^2}{{\mathrm{V}}^2}\right)(\mathrm{V}-\mathrm{nb})=\mathrm{nRT}$ is:

In thermodynamics, the $\mathrm{P}-\mathrm{V}$ work done is given by $\mathrm{w}=-\int {\mathrm{dVP}}_{\mathrm{ext}}$. For a system undergoing a particular process, the work done is,

$\mathrm{w}=-\int \mathrm{dV}\left(\frac{\mathrm{RT}}{\mathrm{V}-\mathrm{b}}-\frac{\mathrm{a}}{{\mathrm{V}}^2}\right)$. This equation is applicable to a