Which of the following statements on critical constants of gases are correct ?

Options

A. Large `(T_(c))/(P_(c))` the value of a gas larger would be the excuded volume .
B. Critical temperature `(T_(c))` of gas is greater than its Boyle temperature `(T_(b))` .
C. At the critical point in the van der Waals' gas isotherm `((delP)/(delV_(m)))_(T_(c))=0`
D. All of these

Explanation

Crirtical temperature `(T_(c))` of gas is less than its Boyle temperature `(T_(b))`
`T_(c) = (8a)/(27Rb), T_(b) = (a)/(Rb)` .