When the value of entropy is greater,then the ability of work

For the reaction $MgCO_3(s) \rightarrow MgO(s) + CO_2(g)$,the value of $\Delta S$ is:

Which of the following statements is correct?

What is the change in entropy when an ideal gas expands into a vacuum?

The standard entropies of $CO_{2(g)}$,$C_{(s)}$ and $O_{2(g)}$ are $213.5$,$5.690$ and $205 \ J \ K^{-1} \ mol^{-1}$ respectively. The standard entropy of formation of $CO_{2(g)}$ is ...... $J \ K^{-1} \ mol^{-1}$.

At $25\,^oC$ and $1\,atm$ pressure,mercury reacts with chlorine to form mercurous chloride: $2Hg + Cl_2 \to Hg_2Cl_2; \Delta H = -31.3\,kcal$. What is the entropy change of the reaction at $25\,^oC$?