When an ideal gas expands isothermally from 5   m 3 to 10   m 3 at 25 ° C against a constant…

The pressure $\mathrm{P}={10}^7 \mathrm{N}·{\mathrm{m}}^{-2}$

Initial volume ${\mathrm{V}}_{\mathrm{i}}=5 {\mathrm{m}}^3$

Final volume ${\mathrm{V}}_{\mathrm{f}}=10 {\mathrm{m}}^3$

Change in volume $∆\mathrm{V}$= ${\mathrm{V}}_{\mathrm{f}}-{\mathrm{V}}_{\mathrm{i}}=10 {\mathrm{m}}^3-5 {\mathrm{m}}^3=5 {\mathrm{m}}^3$

Work done of an ideal gas expands isothermally:-

$$\begin{gathered} \mathrm{W}=-\mathrm{P}∆\mathrm{V} \\ \mathrm{W}=-{10}^7\times 5=-50\times {10}^6 \mathrm{J}=-50 \mathrm{MJ} \end{gathered}$$

Hence, the work done on the gas is $-50\mathrm{MJ}$.