Answer
1 mol of H2 (g) and 0.5 mol O2 (g) at $25^{\circ}C$ have a higher enthalpy than 1 mol H2O (l) at $25^{\circ}C$.
Work Step by Step
Enthalpy can be defined as the total amount of heat in a system. Because molecules in the gas phase have a higher average kinetice energy than molecules in the liquid phase, the 1 mol of H2 (g) and 0.5 mol O2 (g) at $25^{\circ}C$ will have a higher enthalpy than 1 mol H2O (l) at $25^{\circ}C$.
