• # question_answer Direction: An ideal diatomic gas is confined in a cylinder A of volume ${{V}_{0}},$ this cylinder is connected to another cylinder B with the help of tube of a negligible volume. The cylinder B is fitted with a movable piston which can be adjusted from outside. Initially, the piston is adjusted so that volume of B is the same as volume of A i.e., ${{V}_{0}}$. B is evacuated and the stopcork is opened so that gas expands and occupies the volume $2{{V}_{0}}$. [System is thermally isolated from the surroundings].   During this free expansion, the internal energy of the system. Now with the stop-cork open, the piston is slowly moved to compress the gas back to cylinder A at temperature T. For this A) increases B) decreases C) remains constant D) nothing can be said

[c] For present case, $dQ=0,\text{ }dW=0,$ so $dU=0$.