Which of the following quantities does not characterize the thermodynamic state of a substance?

An ideal gas is subjected to a cyclic process $A B C D$ as depicted in the $p-V$ diagram given below. Which of the following curves represents the equivalent cyclic process?

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

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$(a)$ Isothermal	$(i)$ Pressure constant
$(b)$ Isochoric	$(ii)$ Temperature constant
$(c)$ Adiabatic	$(iii)$ Volume constant
$(d)$ Isobaric	$(iv)$ Heat content is constant

Choose the correct answer from the options given below:

An ideal gas follows a process $PT = \text{constant}$. The correct graph between pressure $P$ and volume $V$ is:

The temperature-entropy $(T-S)$ diagram of a reversible engine cycle is given in the figure. Its efficiency is