In a long cylindrical vessel made of perfectly conducting walls, an ideal mono-atomic gas is confined with the help of a light piston, which can slide inside the cylinder without friction. Number of atoms of the gas in the vessel are N. Initially the piston is kept in equilibrium against the pressure p; of the gas with the help of a weight placed on the piston. In this state temperature of the gas is T. Atmospheric pressure is po. 30. When the weight on the piston is removed, the gas expands rapidly and finally the piston settles to a position where the force on the piston due to the gas pressure balances the force due to the atmospheric pressure. Which of the following is a correct description of this process? (a) The gas does no work. Ner{14) Po (b) Work done by the gas is NkT 1. (c) Work done by the gas is NkT In (d)The process is neither isobaric nor isothermal.