Consider a process that is spontaneous at high temperatures but becomes non spontaneous at low temperatures. The sign of ΔH for that process would have to be?
Mg (s) + Cl2 (g) --> MgCl2 (s) [entropy is increasing]
2H2O (l) --> H2 (g) + O2 (g) [entropy is increasing]
2H2O (l) --> H2 (g) + O2 (g) [entropy is decreasing]
2C2H6 (g) + 7O2 (g) --> 4CO2 (g) + 6H2O (g) [entropy is decreasing]
Which has the correct entropy change description?