Use the information given below to calculate the enthalpy change for the reaction: C2H4(g) + H2O(g) → C2H5OH(l)

Rxn 1 H2O(l) → H2O(g) ΔH1 = +44 kJ/mol

Rxn 2 C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l)

ΔH2 = −1371 kJ/mol

3O2(g) → 2CO2(g) + 3H2O(l)

ΔH2 = −1371 kJ/mol C2H5OH(l)

Rxn 3 C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(l)

ΔH3 = −1409 kJ

And a) oxygen i believe

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.