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NEET2026PhysicsChapterActual

Two rigid, thermally insulated tanks A and B are connected by a narrow tube fitted with a closed valve. Tank A has a volume of 5 L and contains an ideal gas at a pressure of 300 kPa and a temperature of 400 K. Tank B has a volume of 15 L and contains the same ideal gas at a pressure of 100 kPa and a temperature of 300 K. When the valve is opened and the gases are allowed to mix, what will be the final equilibrium pre

Options

  1. A200 kPa
  2. B150 kPa
  3. C250 kPa
  4. D400 kPa

Correct answer

B. 150 kPa

Step-by-step solution

Conservation of internal energy for the insulated system gives: U_A + U_B = U_f n_A C_v T_A + n_B C_v T_B = (n_A + n_B) C_v T_f n_A T_A + n_B T_B = n_f T_f From the ideal gas equation, PV = nRT , which gives nT = PV R . Substituting this into the energy equation: P_A V_A R + P_B V_B R = P_f V_f R P_A V_A + P_B V_B = P_f (V_A + V_B) Substituting the given values: 300(5) + 100(15) = P_f (5 + 15) 1500 + 1500 = 20 P_f 3000 = 20 P_f P_f = 150 kPa Answer: 150 kPa

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