An ideal gas undergoes four different processes from the same initial state (figure). Four processes are adiabatic, isothermal, isobaric and isochoric. Out of \(1,\) \(2,\) \(3\) and \(4,\) which one is adiabatic?
 

1. \(4\) 2. \(3\)
3. \(2\) 4. \(1\)

Hint: The type of the process depends on the slope of the graph.

Step: Compare the slope of the graphs.
For curve 4, pressure is constant, so this is an isobaric process.

                          

For curve 1, the volume is constant, so it is an isochoric process.
The adiabatic process curve is more steeper than the isothermal process. Therefore, curve 2 is adiabatic and curve 3 is isothermal. 
Hence, option (3) is the correct answer.