For 1mol of gas, the plot of pV vs p is shown below. p is the...

According to Van der Waals equation,

$( P + \dfrac{a}{{{V}_{m}}^{2}} ) ( {V}_{m} - b ) = RT$

Where, ${V}_{m}$ = molar volume of the gas

$R$= Universal gas constant

$T$ = Temperature

$P$ = Pressure

At point A 'a' is considerable and 'b' is negligible.

So, $( P + \dfrac{a}{{{V}_{m}}^{2}} ) {V}_{m} = RT$

${PV}_{m} + \dfrac{a}{{V}_{m}} = RT$

Compressibility factor ($Z$) = $1 - \dfrac{a}{{V}_{m}RT}$

Hence, the correct answer is $1 - \dfrac{a}{RTV}$