
Process is isothermal
$ \mathrm{w}_{\mathrm{s}}=2 \times 2.303 \log \frac{5.5}{0.5}=2 \times 2.303 \times \log 11=2 \times 2.303 \times 1.0414=4.79 $
$ \frac{\mathrm{w}_{\mathrm{d}}}{\mathrm{w}_{\mathrm{s}}}=\frac{8.65}{4.79}=1.80=2$


$(A)$ Internal energies at $\mathrm{A}$ and $\mathrm{B}$ are the same
$(B)$ Work done by the gas in process $\mathrm{AB}$ is $\mathrm{P}_0 \mathrm{~V}_0 \ln 4$
$(C)$ Pressure at $C$ is $\frac{P_0}{4}$
$(D)$ Temperature at $\mathrm{C}$ is $\frac{\mathrm{T}_0}{4}$

The $P-V$ diagram that best describes this cycle is
(Diagrams are schematic and not to scale)