EAMCET Engineering 2006 Solved Paper

In P−V diagrams process AB is isobaric process in which pressure remains constant i.e, P= constant at all temperatures.
Process BC is isothermal process in which, temperature remains constant i.e., T= constant.
Process CD is isochoric process in which volume remains constant i.e., P−T diagram CD is a straight line passing through origin.
Process AD is adiabatic process which corresponds to process AD in P−T diagram
Hence, the correct P−T diagram is shown in option (a).