$=\int \frac{\mathrm{RTdV}}{\mathrm{V}^3}$
$=\mathrm{RT} \int_2^4 \mathrm{~V}^{-3} \mathrm{dV}$
$=8 \times 300 \times\left(-\frac{1}{2}\left[\frac{1}{4^2}-\frac{1}{2^2}\right]\right)$
$=225 \mathrm{~J}$
$\mathrm{~W}_{\mathrm{BC}} =\mathrm{P} \int_4^2 \mathrm{dV}=10(2-4)=-20 \mathrm{~J}$
$\mathrm{~W}_{\mathrm{CA}} =0$
$\therefore \mathrm{W}_{\text {cyck }} =205 \mathrm{~J}$
Note: Data is inconsistent in process $A B$.
So needs to be challenged.



(Give $2^{1.2}=2.3 ; 2^{3.2}=9.2 ; R$ is gas constant)
$(1)$ The final pressure of the gas mixture after compression is in between $9 P _0$ and $10 P _0$
$(2)$ The average kinetic energy of the gas mixture after compression is in between $18 RT _0$ and $19 RT _0$
$(3)$ The work $| W |$ done during the process is $13 RT _0$
$(4)$ Adiabatic constant of the gas mixture is $1.6$
