19.Which statements are correct?
(A) Sound propagation in air is approximately an adiabatic process instead of an isothermal process.
(B) Sound propagation in air is an isothermal process.
(C) According to the first law of thermodynamics, the change in internal energy of a system is equal to the heat flows into the system plus the work done by the system.
(D) A process whose only net result is to take heat from a reservoir and convert it to work is impossible.
(E) In irreversible change, the total entropy of the system always decreases.