Entropy is maximum in case of

In a reversible expansion,one mole of gas is expanded isothermally at $200 \ K$ till its volume increases $10$ times. Calculate $\Delta S_{total}$ at equilibrium (in $J \ K^{-1}$)?

The enthalpy change for the transition of liquid water to steam is $37.3 \ kJ \ mol^{-1}$ at $373 \ K$. Find $\Delta S$ in $J \ mol^{-1} \ K^{-1}$.

What is entropy?

For which of the following reactions will $\Delta S$ be maximum?

One mole of ice is converted into water at $273 \, K$. The entropy of $H_2O_{(s)}$ and $H_2O_{(l)}$ are $38.20 \, J \, mol^{-1} \, K^{-1}$ and $60.01 \, J \, mol^{-1} \, K^{-1}$ respectively. The enthalpy change for the conversion is $....... \, J \, mol^{-1}$.