For a massless piston undergoing an expansion of $\Delta V$ at constant temperature against a variable external pressure $P$,which equation represents the work done?

Which of the following is an isolated system?

$A$ thermodynamic process $(B \rightarrow E)$ is shown in the graph below. The work done in this process is equal to the area under the curve. Identify the correct area representing the work done.

$1 \, mol$ of an ideal gas is compressed reversibly at a constant temperature of $27 \, ^oC$ from $1 \, bar$ to $4 \, bar$. Calculate the work done in $kJ$.

When $5 \ mol$ of $He$ gas expand isothermally and reversibly at $300 \ K$ from $10 \ L$ to $20 \ L,$ the magnitude of the maximum work obtained is $....... \ J$. [nearest integer] (Given: $R = 8.3 \ J \ K^{-1} \ mol^{-1}$ and $\log 2 = 0.3010$)

An ideal gas expands isothermally from $10^{-3} \; m^{3}$ to $10^{-2} \; m^{3}$ at $300 \; K$ against a constant external pressure of $10^{5} \; Nm^{-2}$. The work done on the gas is: