In thermodynamics, a process is called reversible when.

Consider the reaction at $300 \mathrm{K}$

${\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right)⟶2 \mathrm{HCl}\left(\mathrm{g}\right); △\mathrm{H}°=-185 \mathrm{kJ}$

If $2$ moles of ${\mathrm{H}}_2$ completely react with $2$ mole of ${\mathrm{Cl}}_2$ to form $\mathrm{HCl}$, what is $△\mathrm{U}°$ for this reaction.

A piece of ${\mathrm{NH}}_4\mathrm{Cl}$ is kept inside a balloon filled with some air, having thermally insulated walls. The temperature is kept just above sublimation temperature of ${\mathrm{NH}}_4\mathrm{Cl}$.

${\mathrm{NH}}_4\mathrm{Cl} \left(\mathrm{s}\right)\stackrel{\text{ sublime }}{⟶}{\mathrm{NH}}_3 \left(\mathrm{g}\right)+\mathrm{HCl} \left(\mathrm{g}\right)$.

Which of the following is correct regarding this?

A given mass of gas expands from the state $\mathrm{A}$ to the state $\mathrm{B}$ by three paths $1,2$ and $3$ as shown in the figure. If ${\mathrm{w}}_1, {\mathrm{w}}_2$ and ${\mathrm{w}}_3$, respectively be the magnitudes work done by the gas alonq three paths then