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

$A$ given mass of a gas is compressed isothermally until its pressure is doubled. It is then allowed to expand adiabatically until its original volume is restored and its pressure is then found to be $0.75$ of its initial pressure. The ratio of the specific heats of the gas is approximately:

$A$ cyclic process $ABCD$ is shown in the $p-V$ diagram. Which of the following curves represents the same process if $BC$ and $DA$ are isothermal processes?

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

$A$ cyclic process on an ideal monatomic gas is shown in the figure. The correct statement is:

$A$ monoatomic gas at pressure $P$ having volume $V$ expands isothermally to a volume $2V$ and then adiabatically to a volume $16V$. The final pressure of the gas is $\left(\gamma = \frac{5}{3}\right)$.