For a process to be spontaneous,the total entropy change of the system and its surroundings must be $ \Delta S_{total} > 0 $. This condition is characteristic of which type of process?

Will ice at $273 \ K$ placed in a surrounding at $298 \ K$ melt to form water at $273 \ K$? Prove this statement. The molar enthalpy of fusion of ice is $6.025 \ kJ \ mol^{-1}$.

For the oxidation of iron:
$4 Fe_{(s)} + 3 O_{2(g)} \rightarrow 2 Fe_2O_{3(s)}$
The entropy change is $-549.4 \ J \ K^{-1} \ mol^{-1}$ at $298 \ K$. Despite the negative entropy change of this reaction,why is the reaction spontaneous?
($\Delta_r H^\Theta$ for this reaction is $-1648 \times 10^3 \ J \ mol^{-1}$)

In an isolated system,find the condition for a spontaneous reaction.

Calculate the entropy change in $JK^{-1}$ for the reversible expansion of $5 \ mol$ of an ideal gas at $27 \ ^oC$ from $8 \ dm^3$ to $80 \ dm^3$.

For a reversible spontaneous change,$\Delta S$ is: