In which of the following processes all three thermodynamic variables, that is pressure volume and temperature can change

Which of the following process is feasible at all temperatures?

The process in which changes in pressure, volume and temperature occur simultaneously is

Which of the following thermodynamic condition at constant pressure and temperature is necessary for the spontaneity of a process?

Entropy ( S ) is a thermodynamic variable like pressure P , volume V and temperature T . Entropy of a thermodynamic system is a measure of disorder of molecular motion. Greater is disorder , greater is entropy. Change in entropy of a thermodynamic system is the ratio of heat supplied to absolute temperature.In an adiabatic reversible process, entropy remains constant while in any irreversible process entropy increases. In nature the processes are irreversible , therefore entropy of universe is continuoulsy increasing. The unit of entropy in S-I system is -