==>${\eta _B} = \frac{{{T_2} - {T_3}}}{{{T_2}}} = \frac{{{W_B}}}{{{Q_2}}}$
$\therefore$ $\frac{{{Q_1}}}{{{Q_2}}} = \frac{{{T_1}}}{{{T_2}}} \times \frac{{{T_2} - {T_3}}}{{{T_1} - {T_2}}} = \frac{{{T_1}}}{{{T_2}}}$
$\therefore$ ${W_A} = {W_B}$
$\therefore$ ${T_2} = \frac{{{T_1} + {T_3}}}{2} = \frac{{800 + 300}}{2} = 550K$

$(A)$ 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 $\frac{\mathrm{T}_0}{4}$
(image)
(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 $1.6$
