Which of the following statements is/are correct?

$\mathrm{P}-\mathrm{V}$ plot for two gases (assuming ideal) during adiabatic processes are given in the figure. Plot $\mathrm{A}$ and plot $\mathrm{B}$ should correspond respectively to:

The reversible expansion of an ideal gas under adiabatic and isothermal conditions is shown in the figure. Which of the following statement(s) is (are) correct?

An ideal gas in a thermally insulated vessel at internal pressure $={\mathrm{P}}_1,$ volume $={\mathrm{V}}_1$ and absolute temperature $={\mathrm{T}}_1$ expands irreversibly against zero external pressure, as shown in the diagram. The final internal pressure, volume and absolute temperature of the gas are ${\mathrm{P}}_2, {\mathrm{V}}_2$ and ${\mathrm{T}}_2$, respectively. For this expansion