Q 11-11-007NEETNEET 2020Top questionMedium
Two cylinders A and B of equal capacity are connected to each other via a stop cock. A contains an ideal gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stop cock is suddenly opened. The process is :
Answer: (B) adiabatic
Concept. A thermally insulated system exchanges no heat.
Step 1. Heat. $Q = 0$: adiabatic (a free expansion).
Step 2. Others ruled out. $W = 0$ and $\Delta U = 0$, so the final $T$ equals the initial, but the process is sudden, not quasi-static isothermal; the volume doubles and the pressure halves.
Answer. Adiabatic (Option B).
Solution by Sreeraj P, M.Sc Physics