Obtain an expression for the isothermal compressibility κ = −1/V(∂V/∂P)T for a van der Waals gas.

Obtain an expression for the isothermal compressibility for a van der Waals gas.

a κ=1Vm[RT(Vm−b)3+2aV3m]
b κ=−1Vm[2aV3m−RT(Vm−b)2]
c κ=−1Vm[RT(Vm−b)2−2aV3m]
d κ=1Vm[2aV3m−RT(Vm+b)2]