Calculate the work done in following reaction at $27^{\circ} \mathrm{C}$.

$$ \begin{aligned} & 4 \mathrm{SO}_{2(\mathrm{~g})}+2 \mathrm{O}_{2(\mathrm{~g})} \longrightarrow 4 \mathrm{SO}_{3(\mathrm{~g})} \\ & \left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right) \end{aligned} $$

Which of the following principal of green chemistry suggest use of chemicals made from plant based sources?

Which from following cations will form most stable complex with same ligand?