Which of the following is an irreversible process?

$A$ container with insulating walls is divided into two equal parts by a partition fitted with a valve. One part is filled with an ideal gas at a pressure $P$ and temperature $T$,whereas the other part is completely evacuated. If the valve is suddenly opened,the pressure and temperature of the gas will be

$A$ thermally insulated container is divided into two parts by a screen. In one part,an ideal gas is filled at pressure $P$ and temperature $T$. The second part is a vacuum. If a small hole is now created in the screen,the temperature of the gas will:

Explain the quasi-static process.

In case of free expansion, which one of the following statements is $\underline{\text{WRONG}}$?

Name the process which is associated with dissipated energy process and reduce the efficiency.