The internal energy of a gas obeying P (V - b) RT (where, b is a positive constant and has a constant Cv), depends upon its

Answer: Option C

The internal energy of an gas is given by:
$$\begin{array}{rl}& dU=CvdT-\left[P+T\left(\frac{\left(\frac{\partial V}{\partial T}\right)p}{\left(\frac{\partial V}{\partial P}\right)T}\right)dV\right]\\ & \Rightarrow dU=CvdT+\left[T\left(\frac{\partial p}{\partial T_V}\right)-p\right]\\ & \text{using the given equation:}\\ & P\left(v-b\right)=RT\\ & \Rightarrow \frac{\partial P}{\partial T}=\frac{R}{V}\\ & \Rightarrow dU=c_{v}dT\end{array}$$
Hence internal energy is only a function of temperature.