The following figure shows a $P-T$ graph for four processes $A, B, C$ and $D$. Select the correct alternative.

In the given figure,two processes $A$ and $B$ are shown by which a thermodynamic system goes from an initial state $i$ to a final state $f$. If $\Delta Q_A$ and $\Delta Q_B$ are respectively the heats supplied to the systems,then:

$A$ thermodynamic process is shown in the figure. The pressures and volumes corresponding to some points in the figure are:
$P_A = 3 \times 10^4 \, Pa, \, P_B = 8 \times 10^4 \, Pa$ and $V_A = 2 \times 10^{-3} \, m^3, \, V_D = 5 \times 10^{-3} \, m^3$
In process $AB$,$600 \, J$ of heat is added to the system and in process $BC$,$200 \, J$ of heat is added to the system. The change in internal energy of the system in process $AC$ would be ...... $J$.

The heat energy absorbed by a system in going through a cyclic process shown in the figure is:

Three moles of an ideal monatomic gas perform a cyclic process as shown in the figure. The temperatures in different states are $T_1 = 400\,K, T_2 = 800\,K, T_3 = 2400\,K$ and $T_4 = 1200\,K$. Determine the work done by the gas during the cycle in $kJ$. (Given $R = 8.31\, J\, mol^{-1} K^{-1}$)

The density $\rho$ versus volume $V$ graph is shown in the figure. Find the corresponding pressure $P$ versus temperature $T$ graph.