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⚛️ Physics  ·  Thermodynamics  ·  NEET & JEE

Ideal gas at constant temperature has pressure 4 atm and volume 2 L. If pressure becomes 2 atm, volume:

Answer: 4 L.

  • A 1 L
  • B 2 L
  • C 4 L
  • D 8 L

Correct answer: C. 4 L

Explanation: PV = constant. P<sub>1</sub>V<sub>1</sub> = P<sub>2</sub>V<sub>2</sub>. 4 x 2 = 2 x V<sub>2</sub>. V<sub>2</sub> = 4 L.

Carnot Cycle (P-V Diagram)VP1→2: isothermal expansion (T_H)2→3: adiabatic expansion3→4: isothermal compression (T_C)4→1: adiabatic compression1234Net work done by the gas = area enclosed by the loop 1→2→3→4→1

The Carnot cycle alternates two isothermal steps (heat absorbed at TH, released at TC) with two adiabatic steps (no heat exchange); the enclosed loop area equals the net work output, and η = 1−TC/TH is the maximum possible efficiency between those two temperatures.

Concept context

Laws of thermodynamics, heat engines, entropy, and gas processes.

Read the full Thermodynamics notes →