The relation between the efficiency $\eta$ of a heat engine and the coefficient of performance $\alpha$ of a refrigerator is:

One mole of an ideal gas expands adiabatically from an initial state $(T_A, V_0)$ to a final state $(T_f, 5 V_0)$. Another mole of the same gas expands isothermally from a different initial state $(T_B, V_0)$ to the same final state $(T_f, 5 V_0)$. The ratio of the specific heats at constant pressure and constant volume of this ideal gas is $\gamma$. What is the ratio $T_A / T_B$?

An engine runs between a reservoir at temperature $200 \,K$ and a hot body which is initially at temperature of $600 \,K$. If the hot body cools down to a temperature of $400 \,K$ in the process,then the maximum amount of work that the engine can do (while working in a cycle) is (the heat capacity of the hot body is $1 \,J/K$).

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$(A)$ Isothermal	$(I)$ $\Delta W = 0$
$(B)$ Adiabatic	$(II)$ $\Delta Q = 0$
$(C)$ Isobaric	$(III)$ $\Delta U \neq 0$
$(D)$ Isochoric	$(IV)$ $\Delta U = 0$

Choose the correct answer from the options given below:

Match the following:

List-$I$	List-$II$
$i)$ Isothermal process	$a)$ $0$
$ii)$ Isobaric process	$b)$ $\frac{1}{\gamma-1}[P_2 V_2 - P_1 V_1]$
$iii)$ Isochoric process	$c)$ $\mu RT \ln(\frac{V_2}{V_1})$
$iv)$ Adiabatic process	$d)$ $P(V_2 - V_1)$

The correct answer is:

An ideal monoatomic gas with pressure $P$, volume $V$ and temperature $T$ is expanded isothermally to a volume $2V$ and a final pressure $P_i$. If the same gas is expanded adiabatically to a volume $2V$, the final pressure is $P_a$. The ratio $\frac{P_a}{P_i}$ is