3 moles of an ideal gas (y = 5/3) is subjected to following changes of state.

Identify the correct statement : 

$\text{ State }\mathrm{A}(400 \mathrm{K},2\text{ bar })\underset{\text{ isobaric cooling }}{\stackrel{\mathrm{Reversible} }{\to }}\text{ State }\mathrm{B}$

$\left({\mathrm{T}}_{\mathrm{B}},{\mathrm{P}}_{\mathrm{B}}\right)\underset{\text{ Reversible }}{\stackrel{ \mathrm{isothermal}expansion}{\to }}\text{ State }\mathrm{C}$

$(300 \mathrm{K},1 \mathrm{bar})\underset{\text{ Adiabatic }}{\stackrel{\mathrm{free}expansion}{\to }}\text{ State }\mathrm{D}\left({\mathrm{T}}_{\mathrm{D}},0.5\text{ bar }\right)$