Answer:
Option C
Explanation:
$W=-\int p_{ext}.dV$
Since the process is reversible, pext=p, which gives
$W=-\int p.dV$
Substituting the ideal gas equation for p leads to
$W=-\int \frac{nRT}{V}.dV$
since the process is isothermal,
$W=-nRTln\left(\frac{V_{2}}{V_{1}}\right)$
$-5.187\times1000 J=-n\times8.314JK^{-1}mol^{-1}$
$ln\left(\frac{20m^{3}}{10m^{3}}\right)$
$\Rightarrow n=\frac{5.187\times1000}{8.314\times ln2}mol$
$ =\frac{5.187\times1000}{8.314\times 0.6931}mol=3 mol$