Molar volume (V_m) of a van der Waals gas can be calculated by...

Molar volume $\left(V_m\right)$ of a van der Waals gas can be calculated by expressing the van der Waals equation as a cubic equation with $V_m$ as the variable. The ratio (in $\mathrm{mol} \mathrm{dm}^{-3}$ ) of the coefficient of $V_m^2$ to the coefficient of $V_m$ for a gas having van der Waals constants $a=6.0 \mathrm{dm}^6 \mathrm{~atm} \mathrm{~mol}^{-2} and b=0.060 \mathrm{dm}^3 \mathrm{~mol}^{-1}$ at 300 K and 300 atm is _____ . Use: Universal gas constant $(R)=0.082 \mathrm{dm}^3 \mathrm{~atm} \mathrm{~mol}{ }^{-1} \mathrm{~K}^{-1}$