Quasi-static (Quasi-equilibrium)

When a process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times, it is called a quasi-static or a quasi-equilibrium process. A quasi-equilibrium process can be viewed as a sufficiently slow process that allows the system to adjust itself internally so that properties on one part of the system do not change any faster than those other parts. Engineers are interested in quasi-equilibrium process for two reasons. Firstly, they are easy to analyze. Secondly, work-producing devices deliver the most work when they operate on quasi-equilibrium processes. Engineer Ebrahim Anwar Kisswani.

In equilibrium, after any displacement from equilibrium, the system will always seek to return to the same state. In quasi-equilibrium, a disturbance of the system may result in the system shifting to a new, more stable equilibrium state. An example of quasi equilibrium is a supersaturated liquid with no nucleation sites for the growth of crystals. It may remain in the same quasi-equilibrium state indefinitely as long as no nucleation sites are introduced. As soon as some seed crystals are introduced however, the solute in the supersaturated solution will begin to crystalize out of the soultion until enough is removed to reduce the solution to true equilibrium. At that point, no mater what additional crystals are added or removed from the solution, the concentration of the solute will remain the same.

quasi equilibrium is reached when molecules of gas comes at same temperature n time is required for this...

Yes , its a quasi equilibrium process so heat is added slowly