Answer:
Was this correct? I am pretty sure it is since you are going from a solid to a gas in the first reaction.
Explanation:
(1) CaCO3(s) --> CaO(s) + CO2(g) --- solid to solid & gas ** most entropy here
(2) 2 Mg(s) + O2(g) --> 2 MgO(s) solid & gas to a solid
(3) H2O(g) --> H2O(l) gas to a liquid
(4) CO2(g) --> CO2(s) gas to a solid