In which of the following reaction does the heat change represent the heat of formation of water ?

Options

A. `2H_(2(g))+O_(2(g)) rarr 2H_(2)O_((l)),Delta H = 116 Kcal`
B. `H_(2(g))+(1)/(2)O_(2(g)) rarr H_(2)O_((l)),Delta H = -6.8 Kcal`
C. `H_((aq))^(+)+OH_((aq))^(-) rarr H_(2)O_((l)),Delta H = 13.7 Kcal`
D. `C_(2)H_(2(g)) +2O_(2(g))+H_(2)O_((l)),Delta H = 310 Kcal`

Answer

B