For a van der Waals gas, the ratio (a)/(b) expressed in terms of critical constants is

JEE Advanced levelSingle correct optionDifficulty 3 of 3rg098

For a van der Waals gas, the ratio $\frac{a}{b}$ expressed in terms of critical constants is

T_{c} = \frac{8 a}{27 R b}

, so

\frac{a}{b} = \frac{27 R T _{c}}{8}

. Equivalently, since

P_{c} V_{c} = 3 R T_{c} /8

a / b = 9 P_{c} V_{c}

, which is not among the other options.