Under what condition is mass conserved
A. It is always conserved
Mass conservation is a fundamental principle in fluid mechanics, and it is always conserved under any conditions.
This principle is commonly expressed by the continuity equation, which states that the mass flow rate into a control volume must equal the mass flow rate out of the control volume.
This holds true for all types of fluid flow, whether it is adiabatic, isentropic, or involving barotropic conditions.