The given diagram shows four processes i.e., isochoric, isobaric, isothermal and adiabatic. The correct assignment of the processes, in the same order is given by:

Based on the principles of thermodynamics and the slopes of the curves on a $$P-V$$ diagram, the processes are assigned as follows:

• Isobaric (Process $$a$$): Pressure remains constant, resulting in a horizontal line.
• Isochoric (Process $$d$$): Volume remains constant, resulting in a vertical line.
• Isothermal (Process $$b$$): Temperature remains constant ($$P \propto \frac{1}{V}$$).
• Adiabatic (Process $$c$$): No heat exchange occurs. The adiabatic curve is steeper than the isothermal curve because the adiabatic index $$\gamma > 1$$.

Correct Assignment:

• Isochoric $$\rightarrow$$ Process d
• Isobaric $$\rightarrow$$ Process a
• Isothermal $$\rightarrow$$ Process b
• Adiabatic $$\rightarrow$$ Process c

Final Order:

$$\boxed{d, a, b, c}$$