A cyclic process $ABCD$ is shown in the figure $P-V$ diagram. Which of the following curves represent the same process

An ideal gas is taken through the cycle $A → B → C → A$, as shown in the figure. If the net heat supplied to the gas in the cycle is $5 \ J$, the work done by the gas in the process $C → A$ is ……. $J$

In pressure-volume diagram given below, the isochoric, isothermal, and isobaric parts respectively, are

Graphs below show the entropy versus energy $U$ of two systems $1$ and $2$ at constant volume. The initial energies of the systems are indicated by $U_{1, i}$ and $U_{2, i}$, respectively. Graphs are drawn to the same scale. The systems are then brought into thermal contact with each other. Assume that, at all times the combined energy of the two systems remains constant. Choose the most appropriate option indicating the energies of the two systems and the total entropy after they achieve the equilibrium.

$P-V$ diagram of an ideal gas is as shown in figure. Work done by the gas in process $ABCD$ is