P-V Diagrams & Cyclic Processes
An ideal gas undergoes four different processes from the same initial state as shown in the figure below. Those processes are adiabatic, isothermal, isobaric and isochoric. The curve which represents the adiabatic process among 1, 2, 3 and 4 is

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Answer: (b)
- Slope of - curve: isothermal , adiabatic (steeper since ).
- 1 is vertical (isochoric), 4 is horizontal (isobaric).
- Of the two falling curves, 2 is steeper than 3, so 2 is adiabatic and 3 isothermal.
- So the answer is (b) 2.