For the reaction, $2\mathrm{Cl}\left(\mathrm{g}\right)\to {\mathrm{Cl}}_2\left(\mathrm{g}\right)$, the correct option is

Under the isothermal condition, a gas at $300\mathrm{ }\mathrm{K}$ expands from $0.1\mathrm{ }\mathrm{L}$ to $0.25\mathrm{ }\mathrm{L}$ against a constant external pressure of $2$ bar. The work done by the gas is

(Given that $1\mathrm{ }\mathrm{L}$ bar$=100\mathrm{ }\mathrm{J}$)