Which of the following statements are true? Justify your choices by writing a sentence or two.
A. For a simple compressible substance, the only forces that can act are pressure and gravitational body forces.
B. The thermodynamic state of a simple compressible substance is defined by two extensive properties.
C. For a mixture of liquid water and steam in equilibrium, the state is defined by knowing the temperature and the pressure.
D. For an ideal gas, it is possible to determine the mass-specific internal energy if the pressure and the specific volume are known.