JEE Main · 2019 · 08 Apr 2019 · Shift 2 · Heat & Thermodynamics

Read each curve from its signature on a P-V diagram. An isochoric process holds the volume fixed, so it is a vertical line, which is curve d. An isobaric process holds the pressure fixed, so it is a horizontal line, which is curve a. The isothermal follows $PV=\text{constant}$ and the adiabatic follows $P{V}^{\gamma }=\text{constant}$; because $\gamma >1$, the adiabatic is the steeper of the two falling curves. So the gentler curve b is the isothermal and the steeper curve c is the adiabatic. Read in the asked order, isochoric then isobaric then isothermal then adiabatic, the processes are d, a, b, c.