Which reaction is most likely to have a positive ΔSsys? Which reaction is most likely to have a positive ? 3NO2(g)+H2O(l)→2HNO3(l)+NO(g) CO(g)+Cl2(g)→COCl2(g) 6CO2(g)+6H2O(g)→C6H12O6(s)+6O2(g) 4NH3(g)+5O2(g)→4NO(g)+6H2O(g)