• # 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]. The heat absorbed by the gas is A) $nRT\text{ }\ln \text{ }2$ B) $-nRT\text{ }\ln \text{ }2$ C) nRT      D) $-nRT$

 [b] From 1st law of thermodynamics, $dQ=dU+dW$ $\Rightarrow \,dU=0$ for constant temperature process $\Rightarrow \,dQ=dW$ $\Rightarrow \,dQ=-nRT\,\,\ln \,\,2$ Negative sign shows that heat is released by    the system.