Verified Solution • 2025–26 Session moderate

Q11.6: NCERT Physics - Part 2 THERMODYNAMICS 11.6 Solution: Two cylinders A and B of equal capacity are connected to each…

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following: (a) What is the final pressure of the gas in A and B? (b) What is the change in internal energy of the gas? (c) What is the change in the temperature of the gas? (d) Do the intermediate states of the system (before settling to the final equilibrium state) lie on its P-V-T surface?

Step-by-Step Verified Solution

**Answer:** (a) 0.5×1050.5 \times 10^5 Pa (b) Zero (c) Zero (d) No **Step-by-Step Explanation:** (a) This is a free expansion process. Since the total volume doubles and temperature remains constant (for an ideal gas):
P1V1=P2V2  ⟹  P2=P12=0.5×105 PaP_1V_1 = P_2V_2 \implies P_2 = \frac{P_1}{2} = 0.5 \times 10^5 \text{ Pa}
(b) For free expansion in an insulated container, Q=0Q = 0 and W=0W = 0. Hence, ΔU=0\Delta U = 0. (c) For an ideal gas, if ΔU=0\Delta U = 0, then ΔT=0\Delta T = 0. (d) The intermediate states are non-equilibrium states, so they do not lie on the P-V-T surface .

All Questions in this Chapter

Q11.1 Q11.2 Q11.3 Q11.4 Q11.5 Q11.6 Q11.7 Q11.8

Related Learning Resources & Exam Preparation

Chapter Practice Bank
Practice all topic-wise questions from THERMODYNAMICS
Reference Textbook Solutions
Explore complete chapter exercises for NCERT Physics - Part 2
Competitive PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring